this is bbc news. reporting from washington, i'm laura trevelya n. a return to the cold war chill, britain's prime minister expels 23 russian diplomats in retaliation for the poisoning of a former russian spy the poisoning of a former russian spy in the uk. they have treated the use of a military grade nerve agent in europe with sarcasm, contempt and defiance. us students make the case for gun control, walking out of their classrooms one month after the pub shooting. some time ago i discovered black holes are not that black. remembering a scientific genius as stephen hawking ‘s's discoveries have changed our understanding of the universe. in the biggest expulsion since the

cold war, britain is to kick out 23 russian diplomats. theresa may has pointed the finger at moscow over the poisoning of a former russian double agent and his daughter in england. in response, she will crack down on russian spies, criminals and corrupt elites sheltering in britain. it is the most dramatic action against moscow in 30 years. here is our political editor laura kuenssberg. it was right to offer russia the opportunity to provide an explanation but their response demonstrated complete disdain for the gravity of these events. the midnight deadline came and went, leaving a morning with no new answers. theresa may went prepared to prime minister's questions, ready to announce the biggest diplomatic action against russia since the cold war. they have treated the use of a military grade nerve agent in europe with sarcasm, contempt and defiance. there is no alternative conclusion

other than the russian state was culpable for the attempted murder of sergei skripal and his daughter, and this represents an unlawful use of force by the russian state against the uk. the uk will retaliate. the united kingdom will expel 23 russian diplomats, who have been identified as undeclared intelligence officers. they have one week to leave. this was notjust an act of attempted murder, norjust an act against the uk, it is an affront to the prohibition on the use of chemical weapons and an affront to the rules—based system on which we and our international partners depend. 23 diplomats suspected of being spies have seven days to leave, all high—level contact between the uk and russia is suspended and no minister or member of the royal family will go to the world cup.

some russian state assets could be frozen, with possible laws to crack down on hostile states. in a tense commons, jeremy corbyn was not quite ready to accept the culpability of the russian state. 0ur response must be decisive and proportionate and based on clear evidence. but listen to rising anger asjeremy corbyn turned some of his fire on the tories. it is as we have expressed before a matter of huge regret our country's diplomatic capacity has been stripped back with cuts of 25% in the past five years. it is tradition for the two main parties to stick together on foreign policy. not these two. this is not a question of our diplomacy, of what diplomatic support we have around the world, this is a question of the culpability of the russian state.

foran for an act on our soil. but does this bother the russian strongman? vladimir putin approaching an election, campaigning in crimea, unapologetic. a spokeswoman claiming on tv... "britain does not understand diplomacy or the law "and is full of liars, fully fledged liars." this is notjust a straightforward foreign policy clash but a fight with a country that ignores the norm. number 10 knows this may only be the start. that was laura kuenssberg reporting. us ambassador nikki haley sided with britain at the un, saying russia was

responsible for the poisoning. she spoke at an emergency un security council session called at the request of britain. nick briant joins me from there. very tough words from the us ambassador to the un, tougher than her boss in the white house. what has been the reaction from the russian ambassador there? what we heard from nikki haley was the first time a trump administration official has officially blamed moscow for this attack. earlier in the week former secretary of state rex tillerson says russian involvement was likely, donald trump says he probably is the british findings but have not quite concluded yet that russia was to blame. nikki haley said that. she said russia's crime had to be met with immediate and concrete measures from the security council and the international community, because if they did not do something here then salisbury would not be the last time we saw a chemical attack, it could happen in new york, she said. the russian ambassador was very angry

that this meeting was even held, the british clubbers emergency sessions, the russians tried to hold to do beforehand with procedural wrangling, they failed. the russian ambassador said it should not been before the security council and mayday roger —— rather bizarre and trivialising observation that we needed sherlock holmes to solve the case. can the un security council do any thing given that russia has a veto and can block any concrete action? it is interesting nikki haley setback, because like everybody else in the security council she would know that russia would veto any move to take the concrete measures she proposed. in calling this meeting the british have much more limited ambitions. what they wanted to do was provide a forum, the biggest diplomatic stage in the world, that horseshoe table at the security council, so that the international community could show solidarity with britain and condemn russia's actions. for the most part,

that happened today at the un in new york. what does the un secretary—general himself say about the poisoning link? el ghazi says it is unacceptable, he says these of chemical weapons is a violation of international law. what antonio guterres stopped short of doing was pointing the finger of blame at russia. he said it was not in his job to assign blame, but clearly most members of the security council were prepared to do that, pointing the finger of blame at moscow. nick briant at the united nations, thank you. high school students across america walked out today in protest of gun violence and calling for gun control reform. the walk—outs were 17 minutes long for each life lost in that school. the walk—out comes ahead of a major march on washington later this month. jon sopel reports. the last time we saw children

pouring out of school was that hands on terror after the florida shooting. they came out today with fists clenched, demanding change. what do we want? gun control! are on a bracing cold morning, with their backs turned on the white house, these students fell silent as 17 minutes. a minute for each of those who died at the marjory stoneman douglas school in last month. —— in florida last month. there is no doubting the extraordinary success these youngsters have had in changing the terms of debate on the subject of gun control in america. their problem is that the man who lives on the other side of the fence seems to have got cold feet. when donald trump met youngsters from the florida school at the white house, he seems to offer support for

tougher gun control measures, like raising 22i tougher gun control measures, like raising 221 the age at which you can buy a rifle. he later chided lawmakers had been frightened of the national rifle association. some of your people are petrified of the nra, you cannot be. he has backed off those proposals and the young people are intensifying their campaign. we want common-sense gun law. we want to ban assault rifles. we do not want to be scared in school, it should be our safest institution. we tired of being scared, we want change. we wanted to happen with this protest. this is a curtain raiser to a mass demonstration in washington in ten days. they are a long way from getting what they want, but the power of youth protest has got them further than anyone could have imagined, and they are in no mood to surrender. never again! never again! democrat, man has claimed victory in

a congressional race in western pennsylvania that is virtually a dead heat. the strong showing by the former marine in a district won by donald trump by almost 20 pumps has both parties rethinking their approach to the november midterms. i am joined by the political editor of the nationaljournal. this seat was in the heart of trump country, why couldn't republicans convincingly hold onto it? a democratic basis of energised across the country, even in very republican districts. you will have an energised liberal base so angry president trump that they will show up to every election from dog—catcher to a big congressional race. conor lamb run asa congressional race. conor lamb run as a moderate democrat, very centrist. the won over lots of republican and independent voters who worry about the democrats going too fat to the left. only in january republicans felt really good about their tax cut, hoping they could

sell it in an area. what changed between then and now? jumper and the daily controversies which drive the news cycle and stop republicans talking about issues that interest them, such as the economy —— trump and the daily controversies. people in this district say they are very happy about the state of the economy, but nonetheless a republican seat that trump won by 20 points with won by a democrat even ina good points with won by a democrat even in a good economy. read the tea leaves, what does this mean if you area leaves, what does this mean if you are a vulnerable republican in a seat coming up ahead of the november midterms? there are over 100 house cedes more competitive than this pennsylvania congressional district. this map will be huge come november. democrats only need to win 2a house seats and take back the majority, they only need to win maybe a half ora they only need to win maybe a half or a third of the race is really in play, the odds of democrats taking

back the house have never looked greater after this election. democrat says their own hurdles, not least the senate? the senator is much tougher because the battle grounds for the senator 0rrin very republican states like north dakota, west virginia, some of the most trump friendly states. the battle for the house is not like pennsylvania 18, it is the suburban battle grounds where donald trump has lost significant ground. what made this race so significant is that this is in, as you said, trump country. what lessons do you think democrats will learn, that they can track a bit writer and do well with the right candidate, or they can do anything and win regardless? the former is a much more important lesson, democrats can nominate moderate candidates who are not necessarily liberal on guns, who are not necessarily economically liberal, if they can appeal to the business friendly centrists who do not particularly care for the trump

presidency, that is a ticket to winning lots of these key suburban districts. thank you, josh. donald trump has tapped a cable news commentator to be his top economic adviser. he has been a fixture on us financial television for more than a decade and served in the reagan administration. kudlow replaces gary cullen, who stepped down last week in protest against mr trump's steel and aluminium tariffs. after six months of coalition talks, angela merkel has been sworn in for a fourth term of german chancellor. in italy, 23,000 people have been evacuated from a town on the east coast after a n evacuated from a town on the east coast after an unexploded world war ii bomb was found. 0fficials coast after an unexploded world war ii bomb was found. officials say the 225 kilograms bomb was british made and there was panic when it was accidentally activated jeering the construction of a drain. the device was removed and dropped into the sea. from june, google says the crypto currency bitcoin will be banned from

being advertised on its platforms. the bbc understands google decided to act because it felt there was a lack of consumer protections for highly speculative and complex trades. you are watching bbc world news america. with a growing number of women only co—working spaces being openedin women only co—working spaces being opened in the uk and europe, we take a look. —— in the us and europe. exactly a month afterjacob zuma announced his resignation as president of south africa, his successor, cyril ramaphosa, faces first question and answer in parliament in cape town today. one of the many subjects debated was the controversial issue of land reform. mr ron opposes that land grabs would not be allowed as they would be illegal. the south african government has dismissed a suggestion by a democrat and

australia minister that white landowners should be helped to emigrate. there is a strong case to be made that the use of expropriation without compensation in certain circumstances to advance land reform is entirely consistent with the provisions of our constitution. it is our collective responsibility to use these provisions in our constitution more effectively and directly to drive land reform. tributes have poured into stephen hawking, who reshape the way we think about the universe and broad theoretical physics to the masses. he died at home in cambridge, england early on wednesday. his work on black holes made him a household

name as he overcame his physical challenges. 0ur science editor david shukman looks back at his life. there is nothing like the eureka moment of discovering something no one knew before. stephen hawking had a gift for inspiration, a powerful spirit overcoming an ailing body to allow a mind to roam the cosmos. earning him a place as the most famous scientist in the world. it has been a glorious time to be alive and researching and doing theoretical physics. who else could draw crowds like this? the man who gazed at the stars became one himself. his story poignant and uplifting, his career involved concept so alien and complicated for most it was a struggle to keep up but he explored the strangest of features of the universe, black holes, drawing together the science of the largest things in space with the science of the small, part of a quest to come up with a theory for the universe. he made these incredibly original insights that set up the modern

theory of black holes. and made great contributions to cosmology, and so he was a huge figure. i was devastated, really upset. i met him a couple of times but he had an impact on my life. it is the passing of a great scientist who will be truly missed. as a student his intelligence stood out that at that moment he was given a warning that motor neurone disease would cut his life short. when i was diagnosed, i was told it would kill me in two, three years. i was 21. somehow he kept going. in a high—tech wheelchair and a synthesised voice. i am happier now than before i developed the condition. communicating first by touch, then by twitching a single muscle in his cheek, a daunting burden for anyone. his children saw him as an example. people who live in extreme

circumstances seem to find something inspirational in his example of perseverance and his ability to rise above the suffering and still want to communicate at a higher level. life was not straightforward, his first marriage ending in divorce, as did a second to one of his nurses. claims that he had been physically abused, the case dropped because of lack of evidence. none of this held him back. his book sold at least 10 million copies and everyone wanted to meet him from the pope in the vatican, to the queen. to president 0bama, who awarded him a medal of honour. his fame reached beyond the world of science. your theory of a doughnut shaped universe is intriguing. i may have to stealers. even appearing in the simpsons. i did not say that. yes i did!

in an episode of star trek he had the chance to tease isaac newton. not the apple story again! astounding to think the lord created this in seven days. incorrect. it took 13.8 million years. let's not get bogged down in that again! more recently he was happy to play along for comic relief. he saw himself as an ambassador for science and in this interview told me of his hopes for the large hadron collider. he had a sense of adventure. i am very excited. as you can imagine. i have been wheelchair—bound almost four decades and the chance to float free in zero g will be wonderful. even braving a zero gravity flight. no surprise his death prompted tributes. internet founder tim berners—lee tweeted. .. nasa said...

if you reverse time and the universe is getting smaller. eddie redmayne played him in the film the theory of everything and today said, we have lost a truly beautiful mind. a scientist who delved into the realm of black holes offered an incredibly engaging story that achieved something remarkable, it touched a global audience. that was david shukman reporting. for more on the exceptional life of stephen hawking, i spoke earlier with professor michio ka ku, stephen hawking, i spoke earlier with professor michio kaku, himself a bestselling author and theoretical physicist at the city college of new york. what was it about stephen hawking which so captured the public

imagination? like albert einstein, stephen hawking was viewed by the public as messengers from the stars. the stars are in our dreams, every night when we look outside we see the firmament of the heavens, we are dazzled by the mysteries of the universe. here was albert einstein and stephen hawking saying, come with me, read my books, see my videos and you too can understand the wonders of the cosmic universe. so by exploring the properties of black holes and gravity, what did stephen hawking revealed to us about the universe? we once thought that black holes are totally black, everything that falls in never comes out, even light. when he applied the quantum mechanics to the black hole, thatis quantum mechanics to the black hole, that is atomic physics, he found black holes are actually grave. they emit light ina black holes are actually grave. they emit light in a very faint form, and that revolutionised our understanding of black holes. einstein wanted a theory of

everything. a theory including all of relativity, including black holes, but also the quantum theory, the theory of the arts. that is what stephen hawking did. he was able to create a huge piece of this gigantic jigsaw. as a fellow physicist, what was it about his work he found inspiring? first of all, he set the agenda. physics was sort of meandering in the wilderness for many decades, but he set the agenda, and that is unification, to unify the laws of the universe into a single theory, the theory of everything, the unified field theory that albert einstein set into motion. also he had this great sense of humour that endeared him to millions of people. he was a rock star to the public. here was a man who could go into the depths of the mysteries of nature but also talk to

children and talk to the concerns of the average person. stephen hawking was intellectually inspiring, as you say, and was his determination in the face of illness just as much of an example? when he was 21 years of age she pretty much got a death warrant from his doctors, who said he only had a few years left to live. believe it or not, before then he was a rather average student. he goofed off a bit, he was not focused. when he was given that death warrant he said to himself, i've got to do something with my life, i've got to follow the footsteps of einstein and complete the agenda set into motion by einstein. in even