In a significant foreign policy split, officials admitted that Britain will have some “very difficult” conversations with the President-elect in coming months over his approach to Russia.
Mr Trump said that he will instead join forces with Russia and focus on defeating Isil. He has previously said it would be “nice” if the US and Russia could work together to “knock the hell out of Isil”.
Boris Johnson, the Foreign Secretary, has accused Russia of perpetrating war crimes over the deaths of hundreds of civilians.
The dramatic shift in US policy has prompted significant concern in the Foreign Office, and Britain will use the next three months before Mr Trump enters the White House to try to convince him of the importance of removing President Assad.
Mr Johnson is expected to fly to the US within weeks to meet with senior figures in Mr Trump’s administration and make clear that Britain believes that Mr Assad must go.
The diplomatic tensions emerged as a flotilla of Russian warships which passed through the English Channel has now arrived off the coast of Syria ahead of a major offensive against Isil.
In other developments:
- Sir Michael Fallon, the Defence Secretary, warned that European members of Nato have become “too dependent” on the support of the US after Mr Trump accused them of failing to pull their weight.
- Mrs May will on Monday highlight the importance of globalisation to international security in an ever-changing World. She will also compare the US election to Brexit and say that that the West must recognise the concerns of people who have “seen their communities changed” by migration.
- Nigel Farage, the Ukip leader, met with members of Donald Trump’s inner circle at Trump Tower in New York after saying Theresa May must “mend fences” with the President Elect.
- Marie Le Pen, the leader of France’s far-right Front National, praised President Putin for “defending the interests of his own country” as she criticised US and European aggression towards Russia.
- Mr Johnson boycotted a “crisis” meeting of foreign ministers in Brussels to discuss how Europe will deal with the aftermath of the US election.
- Mr Trump said on Twitter yesterday: “This will prove to be a great time in the lives of all Americans. We will unite and we will win, win, win!”
In his first interview Mr Trump told the Wall Street Journal that his administration will prioritise defeating Isil in Syria rather than removing President Assad.
He told the Wall Street Journal: “I’ve had an opposite view of many people regarding Syria. My attitude was you’re fighting Syria, Syria is fighting ISIS, and you have to get rid of ISIS.
“Russia is now totally aligned with Syria, and now you have Iran, which is becoming powerful, because of us, is aligned with Syria. Now we’re backing rebels against Syria, and we have no idea who these people are.”
He added that if the US attacks President Assad’s regime “we end up fighting Russia”.
The Government had hoped that Mr Trump would be prepared to soften his stance on the issue after winning the election, as he has with several other flagship plans including his pledge to repeal Obamacare. However his interview signalled that he will pursue the alliance with Russia.
Foreign Office officials believe that it will be “incredibly difficult” but emphasised that Britain will not change its position.
“We have been very clear that Assad has no place in the future of Syria,” the official said. “He has the blood of 400,000 people on his hands.”
Another Foreign Office source said that there is hope that Mr Trump will be forced to change his position when he deals with Mr Putin directly.
“There is no doubt that he looks upon Putin as a person who he thinks he can do business with,” the source said. “When he discovers that Putin is not a rational or reasonable guy he might change his mind. This will take time to settle down.”
It came as Vladimir Putin urged Donald Trump to encourage Nato to withdraw its forces from Russia’s borders as part of a bid to improve relations.
Dmitry Peskov, Mr Putin’s official spokesman, said in an interview with The Associated Press that Russia now sees “NATO’s muscles getting bigger and bigger and closer and closer to Russian borders.” He said that as a “confidence-building measure” between the US and Russia Mr Trump could help relations between the US and Russia by “slowing down” or “withdrawing” Nato’s military presence entirely from its borders.
There are also mounting concerns over the future of Nato after Mr Trump suggested that the US may withdraw support from the organisation because European members are failing to “pay their bills”.
Defence spending by European members has fallen from 1.7 per cent of national income to 1.4 percent on average. Belgium, the Czech Republic, Hungary, Italy, Luxembourg, Slovenia and Spain all spent less than one per cent last year.
It came as four Americans were killed yesterday in a suicide bombing inside the largest US military base in Afghanistan, The Taliban claimed responsibility for the bombing inside the heavily fortified Bagram Airfield, north of the capital Kabul, which left 16 other US service members and a Polish soldier wounded.
The assault highlights rising insecurity in Afghanistan nearly two years after US-led Nato forces formally ended their combat operations.
Sir Michael said: “When we go out of the EU, only 20 per cent of the Nato budget be paid by EU countries. That’s not good enough. Therefore, we ask that rich European countries spend more on defence.”
The Prime Minister will on Monday evening say in an address at Mansion House in London that Brexit and Mr Trump’s election shows that “change is in the air”.
She will say: “A year ago, few among us would have predicted the events ahead. A clear, determined decision to leave the European Union and forge a bold, new, confident future for ourselves in the world. And, of course, a new President-elect in the US who defied the polls and the pundits all the way up to election day itself.”
While defending globalisation she will say that Britain and the West must recognise the concerns of those who feel left behind.