welcome to bbc news, i'm mike embley. our top stories: us forces are pulled back from northern syria, as president trump warns turkey he will obliterate its economy if it attacks the kurds. hundreds of arrests as activists worldwide begin a two—week campaign of disruption demanding action on climate change. the fallout from hong kong's demonstrations reaches the basketball courts of america, igniting a debate about free speech and commercial relations with china. and more moons are discovered orbiting saturn, bumping jupiter off the top spot as the planet with the most natural satellites.

president trump has been angrily defending his decision to pull american troops out of northern syria, a move that opens the way for an attack by turkey on kurdish fighters, long—time american allies in the fight against the extremist group the islamic state, but regarded by the turks as terrorists. mr trump has repeated his warning to turkey not to take advantage of the withdrawal, threatening to decimate the turkish economy if they go what he called off limits. the kurds have been leading the syrian democratic forces and have been key to defeating the islamic state extremists in syria. the kurds have reduced areas under is control to virtually nothing, and now hold thousands of is prisoners and their families. president trump and the government in ankara have proposed a 20—mile so—called safe zone on the border to help the return of millions of syrian refugees currently in turkey. the kurds see the american

withdrawal, which has already begun, as a stab in the back. our international correspondent orla guerin sent this report from the border. a pull—out at dawn. us troops leaving observation posts along the syrian border. washington says only a small number of troops were moved a short distance, but kurdish forces fear they are clearing the way for a turkish invasion. turkey's president was viewing serbian troops today, an honour guard on a state visit, as concerns grow internationally about what he is planning for northern syria. before leaving home, he seemed ready for unilateral action soon. "we talked to the americans last night", he said. "and we'll keep talking. we have made a decision,

and as we always say, we might come suddenly one night." that's a major threat for these kurdish fighters from the sdf, the syrian democratic forces, who have fought street—to—street against islamic state, with help from the us. they have been washington's key allies in battle, but with the us pullout, they believe they're being thrown to the wolves. they have vowed to resist any offensive and defend their land at all costs. their spokesman, mustafa bali, told us that an attack by turkey risks giving is sleeper cells a chance to regroup, and even retake some territory. from president trump, a bellicose warning, via his usual undiplomatic channel, twitter.

just last month, american and turkish troops were carrying out these joint patrols at the border. but now, ankara intends to go it alone, taking the battle to kurdish forces that it views as terrorists and a threat to its security. washington has no intention of getting caught in the crossfire, but there is concern in the us and elsewhere about turkey's next moves. there is a growing sense here, on both sides of the border, that the countdown has begun. the pentagon has said that turkey risks destabilising the region and beyond. france has called on ankara not to take any action that could harm the fight against the islamic state

group, and united nations humanitarian officials have said they are preparing for the worst. orla guerin, bbc news, on the turkey—syria border. mike pregent is a senior fellow from the hudson institute. he was a former advisor to general david petraeus and worked with the kurdish peshmergas in iraq. he is in arlington, virginia. how are you seeing this?” how are you seeing this? i see it as a mistake. this is not the right time to abandon a us ally, and if you listen to erdogan‘s words, he is talking about conducting a military operation against terrorists. he is not talking about isis, he is talking about the kurdish ypg. and it doesn't matter if americans just move somewhere else in northern syria. they are abandoning those outposts. they are abandoning areas that have been secured by the ypg against isis, against shia militias,

against isis, against shia militias, against iran, against russia, against iran, against russia, against a side, and now the way bg is left to take care of themselves, and what that likely means is that areas which have been cleared of isis will probably fall back into isis will probably fall back into isis hands as the ypg moves to secure kurdish areas for a turkish invasion. this is security degradation in northern syria. this is risking an isis resurgence ahead ofa is risking an isis resurgence ahead of a 2020 election, and this is really bad for us advisers that have been on the ground working with an ally, having that ally watch you drive away as turkish armoured vehicles move in to northern syria. and i've heard that the turkish air force has actually been conducting airstrikes already on kurdish positions in northern syria. mike, i know you know this region very well. i suppose a lot of people might say to you there has been virtually no american policy in this area for quite some time. surely some policy is better than none, and president trump is threatening turkey, warning

them not to do what you are describing. is that not going to work? i think you are exactly right. we have a very bad policy in syria right now, it is not working. having no policy whatsoever, that is what i look at this as, is worse. this policy of leaving northern syria without a policy is worse. the threat of sanctions against erdogan, the threat of sanctions from lindsay graham, this sort of action by the eu, france and germany, will that be enough to stop a nato ally? —— lindsey graham. it should be, right? it should be, but erdogan is a very different nato ally, and erdogan sees a green light from the white house that he can move in and continue his operations. president trump said something. he said i hope erdogan takes care of our guys in northern syria. he is not going to ta ke northern syria. he is not going to take care of them. he is going to ta ke take care of them. he is going to take care of them. he is going to take care of them by killing them, by going after an ally. that is destabilising for syria and it is

destabilising for syria and it is destabilising for syria and it is destabilising for a rock as well, because these turkish refugees are now going to move into iraq, where it is already a fragile situation with the current involvement. they will push into iraq and other areas. thank you very much indeed. thank you for having me. the us commerce department is blacklisting 28 chinese companies from buying products from the us without washington's approval. american officials say the companies have been involved in china's campaign of repression and surveillance against ethnic uighur muslims in xinjiang province. rights groups say tens of thousands from the minority community are being held in detention camps. china says they are vocational training centres to combat extremism. thousands of climate change activists have been on the streets in cities around the world starting two weeks of global protest. the campaign, co—ordinated by extinction rebellion, is pushing for much more urgent government action to stop rising carbon emissions.

in london, there were more than 250 arrests as protesters blocked bridges and roads in the centre of the capital. our chief environment correspondent justin rowlatt has the latest. there wasn't much the police could do as vehicles blocked key junctions and protesters swiftly chained themselves underneath. careful, mate. we're trying to shut central london to draw attention to the climate and ecological violence. go, go, go, go, go, go go! but officers drew the line when activists tried to set up a kitchen — yep, sink and all — in the middle of trafalgar square. this was a numbers game. there were hundreds of police. there are no official numbers yet, but thousands of protesters. campsites and kitchens quickly sprang up in the heart of government. there was even an impromptu wedding on westminster bridge. cheering and applause it brought parts of central london to a standstill.

everyone's going to lose money. i might as well go home now. my day's finished. i ain't going to earn nothing, am i? it certainly was disruptive. it took hours for police to unglue protesters from this scaffolding tower. and how would you cut this guy free from his hearse? not everyone agreed with the tactics. i think you're hysterical extremists, and you are alienating public opinion, and they ain't going to turn off their lights until you ask them to individually. celebrity supporters defended the action. this is a movement for everybody. this is not about party politics, it's not about brexit, it's much, much bigger than all of that. and it wasn'tjust london. extinction rebellion protests included a mass lie—in in mumbai, roadblocks in berlin, actions in new zealand, and in dublin, too. the crowds are thinning out now, though some activists do plan to sleep over, despite the rain. but it's unlikely to be comfortable, especially when you are chained to a friend.

what are your plans for tonight? to stay here, keep the strand blocked — yeah, keep the blockage up. and aren't you worried the police are going to come and arrest you in the middle of night? no, a cell might be a bit drier than this. # we're getting stronger by the hour... and remember that guy in the hearse? he is still there, though now his passenger is wearing the bike lock. one of the co—founders of extinction rebellion says these dramatic gestures are needed. people have got to get their heads around how serious this crisis is. it's not going away. and carbon dioxide emissions went up 2.796 and carbon dioxide emissions went up 2.7% last year. literally nothing is being done. but there are 13 more days of these direct actions plans, they whether the activists, not to mention the public and police, will have the stomach for that, well, that's another question. asjustin was mentioning in his report, there were protests throughout the globe. our correspondent nada

tawfik is in new york. it's been a scene of really orderly chaos, i would say. the extinction rebellion protesters hitting a lot of the iconic spots of new york city. first, at the charging bull, down by wall street, they sprayed it with fake blood and staged a die—in. around 30 people were arrested between there and the stock exchange, where they continued the protests, before they went up to lower manhattan and blocked traffic on broadway avenue. again, 50 people there arrested. but police have really been trying to contain the protesters, mark out the route and surround them, so it won't get too out of control. and now here, they are beginning what is supposed to be a week of activities, trying to get people signed up and aware of their cause. for months now we have been reporting on the political protests taking place in hong kong, but the fallout from those demonstrations has been felt far and wide. it has now reached the basketball courts of america, and ignited a debate about free speech and commercial relations with china.

the bbc‘s tim allman explains. foran for an american sports fan, this must seem a long way away. violent street protests, anti—government demonstrations. but some people are taking great interest in the future of hong kong. one of them is daryl morey, general manager of the houston rockets, who posted a tweet, subsequently deleted, that contained an image stating fight for freedom, stand with hong kong. the nba has a huge following in hong kong and there was an immediate response. state road because cctv and ten sent holdings, which streams basketball in the country —— tencent, both said they would stop streaming matches. intime sponsors also withdrew support. the nba issued a statement calling his comments regrettable.

daryl morey issued a new statement of his own. but now, leading politicians in washington have voiced concern, worried china is using its economic power to silence its critics. to try to gag a general manager or anybody who is speaking out in favour of the hong kong protesters is wrong, and i hope that basketball will understand that. it's un—american to gag people when they are speaking out on behalf of freedom. the rockets are in japan for a pre—season friendly, but this row over free speech and chinese commercial might is threatening to overs ha d ow commercial might is threatening to overshadow any action on the stay with us on bbc news. still to come: new zealand marks 250 years since british explorer

captain cook landed, and the first encounter between maori and europeans. this was a celebration by people who were relishing their freedom. they believe everything's going to be different from now on. they think their country will be respected in the world once more as it used to be before slobodan milosevic took power. the dalai lama, the exiled spiritual leader of tibet, has won this year's nobel peace prize. as the parade was reaching its climax, two grenades exploded and a group of soldiersjumped from a military truck taking part in the parade, and ran towards the president, firing kalashnikov automatic rifles. after 437 years, the skeleton ribs of henry viii's tragic warship emerged. but even as divers worked to buoy her up, the mary rose went through another heart—stopping drama.

i want to be the people's governor. i want to represent everybody. i believe in the people of california. welcome back. very glad to have you with us. the latest headlines: president trump is accused of abandoning america's kurdish allies as he withdraws us troops from northern syria. hundreds of arrests as activists worldwide begin a 2—week campaign of disruption, demanding much more action from governments on climate change. a new study suggests that e—cigarettes and vaping can cause cancer in mice, which has led researchers to conclude that it's likely very harmful to humans as well. the nyu school of medicine's study is the first to definitively link vaping nicotine to cancer. the practice already been blamed for 20 deaths and hundreds of illnesses worldwide.

dr moon—shong tang, professor of environmental medicine, pathology and medicine led the research, and joins me now. good to talk to you. clearly this is complicated. i am afraid with television we have limited time. tell us why this is important. this is the first time should e—cigarette smoke cause lung cancer in mice. the chemical also can cause, it is proven human carcinogen. the probability of the e—cigarette to cause human cancer based on this study is pretty high. and yet many people of course will be vaping because they feel it is safer than cigarettes. why significantly is it not safer than cigarettes. the

nicotine getting into the cell can transform into the carcinogen just like the tobacco, the nicotine in tobacco. that is one of the reasons tobacco. that is one of the reasons tobacco smoke is a carcinogen. so the nicotine in human cells, also in mice can transform the nicotine, become carcinogenic. it isjust one study, we should make that clear. is this a concern about all vaping, all e—cigarettes? not all of them have nicotine, do they? the purpose of vaping is to get the nicotine, to get the high, so unless you take away the nicotine, otherwise the

commercialjuice all contain nicotine. just to be clear about this, is it yourfeeling nicotine. just to be clear about this, is it your feeling that mice we re this, is it your feeling that mice were perhaps susceptible to cancer orare were perhaps susceptible to cancer or are you sure it was 100% the e—cigarette? or are you sure it was 100% the e-cigarette? well, the control mice, one of the 38 have cancer, but the mice exposed to the e—cigarette, the cancer rate jumped fourfold, nine out of a0 were found to have cancer. so the statistic is very significant, is very strong. thank you very much indeed, professor. you are welcome. a stolen truck has ploughed into several cars in the centre of the german city of limburg. at least 17 people have been injured and one is in a critical condition. the driver of the vehicle, who was also injured, has been arrested.

police said it was too soon to speculate about a motive and that the investigation is still ongoing. germany has been on alert following several jihadist attacks in recent years claimed by the islamic state group. the university of lagos has confirmed it has indefinitely suspended one of its lecturers in the light of a bbc investigation into allegations of sexual harassment of students. boniface igbeneghu was one of several academic staff at two universities in west africa caught on camera offering admission or higher grades to women in exchange for sex. officials at the university of lagos said they have a zero tolerance policy on sexual harassment. mr igbeneghu has also been suspended from the church where he preached. now, take a look at this — this image was captured by the subaru telescope in hawaii. note the white dot highlighted in orange. an hour later, the telescope took this next image, showing the orange dot move with every other celestial object

staying in place. these images confirmed for a research team from the us the discovery of a new moon orbiting saturn. and it wasn't alone. the team have discovered 20 new moons orbiting saturn. and that's important because it has now overtakenjupiter as the planet in our solar system with the most natural satellites. earlier, i spoke with scott sheppard, leader of the discovery team from the carnegie institute for science, about how they achieved such a feet. we took images with one of the most powerful survey telescopes in existence. it's a very large telescope with a very large field of view and we covered the whole area around saturn to find these new moons. so you were using new techniques to analyse old data, essentially, were you? yeah, we took these images a few years ago, but computer power has advanced in the last few years and our computer algorithms have also advanced. so we put these new ideas to some old data and were able to pull out 20 new moons of saturn. they're very faint moons,

they're fairly small — three to five kilometres in size. but they were all there in the data and we were able to pull them all out. so they're just kind of points of light at the moment. you don't know very much about them. why are they particularly of interest? we're interested in these outer moons of saturn because we believe they‘ re the remnants of a planet formation. most of the objects that are in the giant planet region where jupiter and saturn are have been either incorporated into the planets or rejected out of the area, and so we think these moons were captured by saturn just after the planet formation process, so we think these are the building blocks of the planets, the last remnants of those small objects. so, does that mean if you can analyse them more closely, you will know more about how the planet itself was formed? yeah, we want to determine the composition of these objects to see basically what the planets were originally made of, the building blocks of the planets. and these objects are very faint, they'are just points of light

—— they're just points of light so we'll need the next generation of telescopes to really analyse these objects and determine what they are. we think they're probably comet—like objects, so probably half water ice and half rock, that kind of material. just very quickly, i have to ask you a question on behalf of schoolchildren around the globe. i think you're holding a competition to name them. how is that going to go? how can people enter? yeah, we want the whole world to try and name these new saturn moons. they have to be named after inuit, norse or gaelic mythology and you just go to twitter and you type in the hash tag #namesaturnsmoons and tell us what you want to name them. videos and photographs are highly recommended to get your name accepted. you heard it here. let's get some of the day's other news. hong kong's government is considering restricting access to the internet to try to contain the protests. an emergency law banning the wearing of face masks only stoked tensions at the weekend and led to more clashes with police. dozens of people have been arrested for flouting the new law. the swedish king has removed five of his grandchildren

from the royal house. they will no longer have the title of royal highness and will not perform official royal duties, but will remain members of the royal family and retain their titles. it reflects a wider view that there is no need to pay so many members of the family for official duties. new zealand is marking 250 years since the british explorer captain james cook set foot in the country. a replica of his ship, the endeavour, has arrived at the same spot in gisborne to a mixture of celebrations and protests. our correspondent phil mercer is there. the arrival of the replica ofjames cook's ship the endeavour has once again reignited debate here in new zealand about the legacy of captain james cook. to many maori people, his arrival was the start of a brutal colonisation. they say the effects of invasion, as they call it, are still felt today. maori people make up about 15% of the population, but they suffer disproportionately

high rates of ill health, imprisonment and suicide. to many other new zealanders today, it's a time of great celebration. they are commemorating an important chapter in their european history. we have seen hundreds of people gather around the bay today to watch this ship sail into gisborne harbour. 250 years ago was the first time that europeans had contact with maori people on the ground here in new zealand. a very significant day, a very divisive issue when we consider the legacy of captain james cook. was he a barbarian, was he an invader or was he a father of the nation? phil mercer there in gisborne, new zealand. there is much more on all the news anytime on the bbc website. and you can get in touch with me

and most of the team on twitter. thank you for watching. hello there. this week is looking typically autumnal, quite unsettled, windy at times and there will be plenty of showers in the forecast. also, some sunshine, it won't be a washout all the time, but when you catch one of these showers, they will often be quite heavy. maybe with a rumble of thunder and some hail mixed in too. all down to low pressure, which will be just to the north—west or to the north of the uk over the next few days and indeed for much of the week. so our air will be coming in off the atlantic with these weather fronts bringing in bands of showers. one thing you will notice, though, it's not going to feel particularly cold, we will have our air source coming in off the atlantic from a west or a south—westerly direction most of the time. so that means around average temperatures through the day. and at night, it should keep the frost and fog at bay.

so for tuesday, it's going to be a bright, sunny start across many central and eastern areas, but plenty of showers across to the west will tend to work their way through, and they'll be blown in on a strong wind. so they'll move through quite quickly despite them being quite heavy in places. like i said, with thunder and hail. and the winds will be gusty, very squally, a0—50mph in places, so the showers won't be with you for long. temperature—wise, highs of 16 or 17 degrees, generally the low—to—mid teens further north, particularly where you hold on to frequent showers. as we head to tuesday night, it looks like those hours, —— showers, blustery, continue across northern and western areas, central and eastern areas may tend to turn drier, in fact, with clear skies. most temperatures no lower than around 7—10 degrees. for wednesday then, low pressure still with us just to the north of the uk, tightly packed isoba rs, so another windy day, and these weather fronts producing bands of showers. there will be one heading into parts of england and wales, i think, through wednesday morning.

so we'll see an enhancement of showers across western areas through the morning into the afternoon. there could be a cluster of some heavy, maybe thundery ones pushing across south wales and southern england. again, further north, closer to that area of low pressure, this is where we'll see most of the showers across western scotland. temperatures on wednesday probably a notch down on tuesday's values. on into thursday, low pressure again to the north of the uk, it's going to be another pretty windy day. bands of showers moving from west to east, most of them again across the north and the west of the country. eastern areas may tend to stay dry with some showers arriving through the afternoon later on. temperatures again 13—16, maybe 17 degrees in the south—east. and it remains unsettled from thursday onwards, you can see sunshine and showers, those temperatures around the seasonal average, and it remains windy as well.

this is bbc news. the headlines: president trump has been angrily defending his decision to pull american troops out of northern syria — a move that opens the way for an attack by turkey on kurdish fighters. mr trump has threatened to "decimate" the turkish economy if they go what he called "off limits." thousands of climate change activists have begun two weeks of global protest. the campaign, coordinated by extinction rebellion, is pushing for more urgent government action to stop rising carbon emissions. in london, there were more than 250 arrests, as protesters blocked bridges and roads in the capital. a replica of the endeavour has been marking the 250th anniversary of captain james cook landing in new zealand. he'd set sail from the yorkhshire port of whitby. it's not without controversy, as some maori communities see cook's arrival as the start of the marginalisation of the maori people.