floodwaters rise and tensions flare as russia and ukraine trade blame for a massive dam burst. in just a matter of hours, the world—famous new york skyline, hidden from view by hazardous air — tens of millions in north america are warned about dangerous air quality. rishi sunak announces the first global summit on artificial intelligence ahead of talks withjoe biden in washington hello i'm sumi somaskanda. ukraine's president volodymyr zelensky says he is shocked by the lack of help from international aid agencies, following the destruction of part of the kakhovka dam.

water continues to surge down the dnipro river hich divides russian and ukrainian—controlled territory nd thousands of people have been moved from their homes in the region of kherson. ukrainians and russians are blaming each other for the damage. water levels are still rising rapidly, and ukraine's prime minister has urged the united nations, the international red cross and other agencies to act immediately to help those in areas controlled by russian occupiers. president zelenskyy says hundreds of thousands of ukrainians have been left without drinking water. emergency services are searching far and wide for people stranded by the floods. our ukraine correspondent james waterhouse reports from kherson. this eastern bank of the dnipro river is currently a no—man�*s—land. neither russia nor ukraine control here. now, no—one can live here. the ukrainian army drone spotted catalina trapped in her home.

they tried to drop her water — no luck. her son then makes the crucial catch. they're both taken to kherson, along with her daughter, maria. a city once occupied by russia, then liberated by ukraine, now on its knees. translation: we managed to find the simplest boat, i but my father and a neighbour got carried away in it. it came loose and the current was too powerful yesterday. rowing didn't help. so we were left with my kids, the three of us, for the night. it feels like we lived a whole life in one day. otherwise, we're very grateful to everyone. this once innocuous road, now a slipway rescue boats. as people are brought to safety from submerged streets, the relief is palpable. to move through the streets now, you need one of these. the silence reflects just how uninhabitable pockets of the city have now become. that sign would normally be at head height.

the trunks of those trees are completely submerged. rescue teams are trying to help people, and you can see how they'd be trapped. the water is cloudy. kherson, after everything it's gone through, is a city on its knees. shelling is a common occurrence in kherson. the russians might have left, but they're never far. it takes a lot for locals to be forced to leave here, but, for a growing number, that moment has come. president zelensky has criticised the international response to what's happened, accusing the un and red cross of not being here. in two days, kherson has partly been submerged by the dnipro river. the flooding is more extreme on the eastern bank — part of ukraine, but controlled by the russians. there is a military dynamic to the kakhovka dam's destruction — it makes any ukrainian offensive from here more complicated.

as for those living here, it's gone from difficult to the verge of impossible. james waterhouse, bbc news, kherson. the damage caused to the dam in ukraine has happened at a significant moment in the war,just as ukrainian forces seemed to be embarking on their long—awaited offensive against the russians.this is the front line in the conflict. it's some 600 miles long, with the areas under russian control shown in red. we know that fighting is continuing around the city of bakhmut. earlier this week, there were reports of ukrainian attacks in the area west of donetsk. around zaporizhizhia, the russians control huge areas of the region but the ukrainians are still in control of the city. our correspondent quentin sommerville is there. i've been to those very front lines where there's an offensive going on right now, and it's very difficult ground to attack across. it is wide open fields with very little cover, and those fields are peppered with russian artillery craters. when we were there a few months ago, the men that we were speaking to in the trenches told us that the lines had only moved perhaps ten,

or maybe a few hundred metres — well, they're certainly moving now. we're getting reports ukrainian forces have gained five kilometres, perhaps even ten kilometres of territory. it's not just the fact that they're moving, it's how they're moving, which gives us an indication of how the main offensive will go. they're using armoured vehicles, they're using tanks, they're moving fast, they're attacking from multiple different axis. but they're facing a very formidable foe, because the enemy on the other side of the line has been there for a long time, and has dug in and has built formidable defences. they have plenty of artillery, plenty of anti—tank missiles, as well. so that much—anticipated main offensive is coming, and the ukrainian commanders will be looking at the lessons of these earlier offensives — but let's not forget, huw, just the other week, president zelensky said that ukraine was ready for this counteroffensive

but he warned that in the coming days and weeks and months, many lives would be lost. the ukrainian soldiers we've spoken to have a solemn understanding of that. they realise there's a lot riding on this counteroffensive — perhaps everything. officials have warned tens of millions of people across north america they're at risk of breathing in hazardous air. ottawa and new york are facing the brunt of the dangerous air quality, in fact they briefly had the worst air quality in the world overnight — you can see that orange haze hanging over new york in these images. major league baseball games have been called off in new york and philadelphia. a time lapse of new york city

captured by earthcam and shows just how quickly the orange haze covers that famous skyline. officials say it is likely the worst wildfire season on record in canada, with climate change increasing the risk of hot and dry weather. hundreds of american firefighters have landed there to help battle the fires raging across the country. cbc reporterjennifer yoon is in montreal and has more on the fires. thank you forjoining us. can you tell is the situation where you tell is the situation where you are? there is an unprecedented wild fire season here in canada, from coast to coast, wild fires burning out of control. 3.8 million hectares bud, the majority of the fires are still not under control and over 20,000 people who are displayed and cannot return to their homes have been evacuated. in quebec, but in the north it is a different story. we have towns that have been evacuated. people told to leave late at night last night, grab their stuff, rush out, grab their pets and had to safety. this is what is happening in quebec and in canada.

our correspondent samira hussain is in new york and has more for us on the hazardous air quality there. i mean, just take where i am right now in lower manhattan, just away from the world trade centre — and if you look behind me, well, it should be newjersey and some office buildings that we would regularly see any time that we're in this area, but they are rendered pretty unvisible right now. it is a similar scene throughout parts of the eastern seaboard, where you've seen just the air quality has become really quite poor. here in new york city, public schools have been ordered to not have any outdoor activities, and the mayor of new york has said that, "look, don't go outside if you don't have to, and if you do, you should be wearing an n95 mask." but of course, i took to the streets of new york to ask new yorkers what they make of the haze. have you ever seen anything like this? no, i said it was

like the apocalypse. that's what i feel like, it's very scary. and dangerous, too! i haven't had a mask on since covid, but now breathing this — i don't want to breathe this in, it's very dangerous. no, never seen anything like this before at all. this is bonkers. ijust walked out now, - and i was completely shocked by the haze and the — - it's like, you can smell this horrible, horrible smell. it feels like a video game, it don't feel real, it smells weird. it'sjust crazy, like my lungs feel weird right now. i'm feeling sick, so i got to get home, yeah, i don't know. well, it is all coming from the wildfires in canada — right now, there are more than 400 fires raging in the country from the west over into the east, and only half of them are actually under control right now. and so, it's the wind that's bringing that air down to new york, and even as far down as the carolinas. i'm and the air�*s actually quite polluted, as well, because in it, there's this fine dust that is particularly irritant — a particular irritant, rather, for people with lung disease and asthma, which is why there's so much caution around people staying indoors, especially if you're more vulnerable.

so what does this hazardous air mean for our health? earlier, i spoke to the national senior director of clean air advocacy with the american lung association, william barrett. it's great to have you on our show. , ., . ., show. here in dc, we have code red inequality — show. here in dc, we have code red inequality today _ show. here in dc, we have code red inequality today stop - show. here in dc, we have code red inequality today stop what l red inequality today stop what should residents up and down the east coast of the us be worried about? being exposed to particle emissions in the form of wild fire smoke is a serious health risk. we want to make sure people are aware of those hard levels that they are hard to miss but we want to make sure people are keeping track of that and any change in conditions and doing their best to stay indoors and reduce their exposure to particle pollution in this smoke. what is it that makes it so toxic? when you breathing particles, these are fine bits of smoke, ash and other things, they can get deep into our lungs and actually

bypassed most of the body's defences and create negative health consequences for our respiratory systems that asthma attack, worsening conditions. they can have an impact once they get into the bloodstream on cardiovascular issues. including heart attacks, strokes. so a range of negative health consequences both in terms of breathing systems in the body. some people have to go outside, some work outside, should people be wearing masks, what do you recommend? first and foremost, we do not want people to get a false sense of security. we want to make sure people stay indoors. if you have to be outdoors, we encourage to limit heavy exertion activity.

you should not be exercising into this kind of smoke exposure and follow—up masks, we do not want people to relyjust on surgical masks because they will not provide the same level of protection potentially as an and 95 miles. we want to make sure people are taking the right precautions. and n95 masks make it difficult for people with lung conditions to be able to breathe site to make sure you make the right decisions. thank you forjoining us on our show. thank you so much and stay healthy. around the world and across the uk, this is bbc news. bbc news — bringing you different stories from across the uk. every week, these volunteers are testing the water quality — and the results are getting worse. extremely frustrating because you can see this area of outstanding natural beauty being degraded. what volunteers have found is one of the main problems with this river are high levels of cow poo and chicken poo. it's being spread as a manure, and when it rains, of course, it then washes off the land

and seeps down into the river. the poop produces phosphate which attacks the water quality — and with the number of chickens being farmed in the area going up, the wildlife in the river has been going down. two years ago, the friends of the lower wye action group were set up with a single goal — to have a clean, pollution—free, healthy river and valley. i'm hoping what we're doing will make a difference. for more stories from across the uk, head to the bbc news website. here in the us, former president donald trump says that nobody has told him that he is being indicted. he made that statement on social media following reports in the us that a source close to the former president says he is the target of a federal criminal investgation into the possible

mishandling of classified information. it's the latest news in a string of legal challenges facing mr trump as he's vying for the republication nomination. i discussed the significance of these reports earlier with tom lobianco, national political reporter at the messenger, and democrat political strategist mary anne marsh. we do not exactly how that will play in terms of galvanising or driving voters away from him in the primary one thing i've heard from a lot of strategists inside the other campaigns that are running, this is what they are running, this is what they are all prepping for is the possibility it becomes a logistical nightmare for donald trump. wejust logistical nightmare for donald trump. we just found logistical nightmare for donald trump. wejust found out logistical nightmare for donald trump. we just found out there is another grand jury this week in florida, hypothetically he does not have two leave mar—a—lago for that one but he still has georgia, new york, potentially washington, dc, which legal teams does he work with? it creates a logistical nightmare and on top of that,

do they impose, do the courts impose gag orders, while the front runnerfor the impose gag orders, while the front runner for the republican nomination while he is in the middle of the republican nomination and potentially even before the debate stage. in august. before the debate stage. in au~ust. ,~ ., before the debate stage. in au~ust. ., ~ august. maryanne what you think will this be _ august. maryanne what you think will this be a _ august. maryanne what you think will this be a logistical _ will this be a logistical nightmare or is this something where president trump emerges somehow stronger?— somehow stronger? logistics will be an _ somehow stronger? logistics will be an issue _ somehow stronger? logistics will be an issue for _ somehow stronger? logistics will be an issue for donald i will be an issue for donald trump, none of the candidates in the race have the skills or standing to take out donald trump and neither will any indictments or potential convictions do that either, there was a poll that came up this afternoon that said 60% of republicans did not see withholding documents or being indicted as a problem, as an issue. it will hurt him in the general election but donald trump will be the nominee, none of this. and you will have a rematch between donald trump and joe biden and donald trump has been masterful at taking

theseissues has been masterful at taking these issues and turning them to his favour that only whips up to his favour that only whips up the fervour among the 38 or 40% of republicans who are with donald trump no matter what and fuels their conspiracy theories about him. he will use this to his advantage but there is no—onein his advantage but there is no—one in the field right now on any other issue that can stop donald trump right now and i do not see any of it coming up, from being the nominee. he basically at this point, could have this wrapped up by super tuesday in march. i5 have this wrapped up by super tuesday in march.— have this wrapped up by super tuesday in march. is only going to net tuesday in march. is only going to get more _ tuesday in march. is only going to get more interesting, - tuesday in march. is only going to get more interesting, thank| to get more interesting, thank you for your insights. great to have you on the show. today, the man who served as trump's vice—president, mike pence, entered the race for the white house, and for the first time condemned his former boss. mr pence also talked about uniting americans. take a look: whether it was when the towers fell and people rushed across the country to search for their relatives or whether it was when the wind blew here in iowa and the floodwaters rose.

so i ask you to remember who we are. if you are tempted to despair, we are americans and there is nothing we cannot accomplish together. i spoke to cbs news chief election and campaign correspondent, bob costa, who was covering mr pence's campaign launch in iowa. thank you so much forjoining us from iowa tonight. this is the strongest public rebuke of trump we have seen from mike pence and you asked him why. let's watch that video. you took on trump injanuary. why was it so important? it's time. time for what? he says it is time. what you think he meant by that? for more than two years, former vice president mike pence has tried

to navigate his post vice—presidential career on his own terms, talking about conservatism, planning a possible 2024 presidential bid and avoiding talk, mostly, of the january 6 capitol attack. now, as he is a witness in the ongoing special counsel investigation and january 6 continues to dominate the american political scene, mike pence has decided to take this issue on directly and talk about trump, talk about how the former president handled that day and the pressure campaign. it is pence's way of dealing with the political reality of his presidential candidacy. do you think it is a strategy that will work? most other candidates avoided taking on the former president. pence's advisors tell me that at the end of the day he may try to avoid talking

about january 6 but it will always rev up on the debate stage, in conversations with voters, so from day one they wanted to outline pence's position and to say that he did something that was admirable, in their opinion. he followed the rule of law and did his duty by not trying to overturn the 2020 election. they are trying to cast his experienced during that day as a positive response to campaign and they are pitching it to conservative voters in iowa and elsewhere as a time when pence followed the rule of law and did something in line with conservative values. do you have a sense in iowa of how much support he has among voters? iowa is an important early voting state. sometimes the best reporting in iowa and across the country comes from talking to voters. and when i spoke to in iowa today, i asked them that question. how do you see the pence campaign in iowa? and many told us he faces an uphill climb, difficult and winding road ahead because he is not just facing down the former

president, but new political stars like the florida governor ron desantis and others running for the nomination. pence has to get through all of that and convince voters in iowa that he is the best positioned religious conservative to be their standardbearer for a general election. this is a historic playbook he is following in a way. if you look back at the campaigns of mike huckabee in 2008 and rick santorum in 2012, senator ted cruz in 2016, they all used iowa as a platform for them to outline their conservatism, go to churches and religious voters and use that as rocket fuel for their campaigns down the line. always great to talk to you. let's take a look at some other stories making the headlines around the world. tests carried out on human remains found dumped in a ravine in mexico suggest they are those of workers who disappeared from a call centre. eight young employees were reported missing

in the days leading up to the discovery last week. doctors in rome say pope francis is recovering well after undergoing surgery for a hernia and other abdominal issues. they say the procedure was planned after the pontiff had reported being uncomfortable for several weeks. the uk's prime minister has begun a two—day trip to washington. support for ukraine, ai and economic cooperation are high on his agenda. rishi sunak, who arrived in washington in the early hours of wednesday morning, is due to meetjoe biden on thursday. after his arrival, he visited arlington national cemetery where he laid a wreath at the tomb of the unknown soldier. and he met the speaker of the united states house of representatives, kevin mccarthy. the speaker lauded the "long history," and shared beliefs shared by the two nations. the prime minister also met us senate majority leader chuck schumer, a senior democrat. during talks with president biden tomorrow, he's expected to renew pledges of british

support for ukraine. he will also lobby for the uk to play a leading role in regulating artificial intelligence. he's been speaking with our political editor chris mason — who asked him this question on al. i want to make sure that in the uk we can realise clear benefit of ai, be that in drug discovery or other areas, but at the same time we must put guardrails in place to protect ourselves, our people, from the very real risk that it poses, risks that the creators of ai itself have highlighted. i will talk to president biden about that tomorrow. i think the uk is well placed to lead and shape the conversation on this. i spoke to chris after his interview with mr sunak. the uk will host a global summit in the fall on al. why is this a priority for the prime minister? it is a demonstration of the uk, personified

at the moment by rishi sunak as prime minister, but it would be the same challenge for any future prime minister, of the uk trying to find its place in the world after brexit, having left the european union. even though the referendum on brexit was back in 2016 there was a lot of turbulence immediately after, then there was covid and then the british governments falling over themselves every 45 minutes and being replaced with new prime ministers and it is only now that we are beginning to see, in rishi sunak, an attempt to find a place in the world where the uk has a sovereignty that it did not have before and is not part of an international bloc that comes with something of a megaphone. that is why, particularly on the subject of artificial intelligence prime minister makes the argument he thinks the uk is relatively well—placed, given the scale of the sector in the uk, to try and argue we can be some sort of international convener around the question of ai and its regulation. do you think that effort is working to establish the uk again on the global stage,

especially from the washington perspective? it is just starting and it is hard to be certain of that. when you speak to the prime minister as i did earlier and you say to him, hang on, look at this from the perspective of washington, a superpower here in america, who does it pick up the phone to when it wants to talk about artificial intelligence or anything else when it looks in europe's direction? it will often pick up the phone to brussels, to the eu. how does the uk find space in that world? the argument, and brexit proponents have made this argument for years, is about being distinctive and not falling under the umbrella of an organisation that will find a way of calibrating its view on something like ai through the prism of the different views of over 20 different member states as opposed to what might specifically be in the interest of the uk. i think it is a case, the question about al and its regulation, of the uk trying to find its place when it comes to these global

issues in which the uk may attempt to say that it has some sort of competitive advantage that it can bring to the wicket in international discussions. great to have you in the studio here in washington. it is not all business for the prime minister while he visits washington, he took a trip to the ballpark to round out the day. he watched the washington nationals take on the arizona diamondbacks during his trip, fans were treated to a military fly past and both god save the king and the star—spangled banner played by royal marines and us military bands, but the promise to did not strike up a good luck charm for the nationals who lost their fourth game in a row. that's our show from here in washington. we will hand over to our team in london, more news at the top of the hour. dawn isjust breaking

in london. stay with us here on bbc news. hello. well, our weather's been stuck on repeat a bit over the past few weeks, hasn't it? it's been largely dry and settled, with the best of the sunshine towards the west. but things are changing, as we head through the latter part of the week and into the weekend, the heat and the humidity are going to build, and there's a chance of some thunderstorms, as well. now, heading through the course of the weekend, these are the sort of temperatures we could see — mid—to—high—20s, very small chance, one or two places possibly getting near 30 celsius. but we do have a heat health alert that's been issued by the met office and the uk health and security agency, too. so, high pressure has been in charge of our weather, but cast your eyes down towards the southwest — this is storm oscar, and over the next few days, that low pressure is going to push closer towards the uk — and as it does so, we'll draw in these winds for more of an easterly, or even southeasterly direction, so that is what is bringing us the warmer weather. but for the here and now, still in that cooler air mass

at the moment, so thursday morning dawns with quite a bit of cloud for central and eastern areas, and, like recent days, that cloud will burn back towards the east coast through the day. so lots of strong sunshine — you'll notice the breeze blowing through east anglia, southern england, through the english channel, too — but the warmest spots probably getting up into perhaps the mid—20s, still mid—teens, though, for parts of eastern scotland and northeast england. and grass pollen season will be reaching its peak soon, so very high levels of pollen — you'll notice that across england and wales, if you suffer from hay fever. now, thursday evening and overnight into friday, the cloud rolls back westwards once again, as it has done over previous nights. it's probably a little bit less cold, though, temperatures staying up around about 8 or 9 degrees for most of us into friday, we'll see that subtle change in wind direction. so friday, mostly dry again, still a bit of cloud lingering in the northeast, but not as much as recent days. breeze blowing in from the east or northeast, across the southern half of the uk, but look at those temperatures — more widely, we're getting up to about 211—25 celsius, still a little bit cooler than that again in the northeast. heading into saturday, a few showers start to work in, initially for the far

southwest, they'll creep their way northwards and eastwards — perhaps northern ireland, central parts of england and wales could catch some of those hit—and—miss thundery downpours. so we're looking at temperatures probably warmest for many central and eastern areas on saturday. temperatures above average for all of us, as we head through the next five days or so. chance of some heavy showers — it looks like they ease away for many of us through the course of next week. bye— bye.