United Kingdom urges Putin to end support for 'toxic' Assad

"He is poisoning innocent people with weapons that were banned 100 years ago - and he is poisoning the reputation of Russian Federation".

After last Tuesday's chemical attack, Mr. Trump said his attitude toward Mr. Assad "has changed very much" and Mr. Tillerson said "steps are underway" to organise a coalition to remove him from power.

"Now is the right moment to talk about how we can push for a peace process in Syria within the worldwide community - with Russian Federation, with Iran, with Saudi Arabia, with Europe, with the United States", he said as he arrived.

Russia's foreign ministry said in a statement that it hoped for "productive talks".

Even before Trump ordered last week's strike on the air base in retaliation for a nerve gas attack, Tillerson's visit was certain to be dominated by thorny issues, including Russian interference in the 2016 USA election, an apparent violation of an important arms control treaty, and seeing what cooperation, if any, is possible in the fight against Islamic State.

The United States has concluded that Russian Federation knew ahead of time that Syria would launch a chemical weapons attack last week, a senior USA official says. Tillerson said it was clear the USA saw no role for Assad in Syria's future, given that he had lost legitimacy.

"I think the Russians need a way out and a way forward", Johnson said. But they were divided about how to deal with Syria, and Moscow. It said the outcome of the discussions is important not only for the Russia-U.S. relationship, but "for the overall atmosphere on the world stage". The official also didn't provide details for the military and intelligence information that form the basis of what the Pentagon now believes.

It was an unforeseen turn of events for Trump, who praised Putin repeatedly during last year's election campaign and said he would like to work more closely with Russian Federation to defeat Islamic State.

USA allies appear to be moving ahead with their own policies for dealing with Syria after attempts by top Trump administration officials to articulate a plan leave key questions unresolved. US officials in Washington have also raised that prospect.

Earlier, Downing Street re-iterated the Government's support for the USA missile strike while calling for a renewed diplomatic push to end Syria's six-year civil war. But Tillerson also said that the top US priority in the region remains the defeat of Islamic State militants.

"The strikes aren't necessarily a bad thing for Russian Federation", said Andrew Tabler, a fellow with the Washington Institute for Near East Policy.

In response, the United States says it destroyed a fifth of Syria's operational aircraft in an air strike on the Shayrat airbase last Thursday and said further strikes could take place.