Britain will attempt to sway Mr Trump’s approach to Russia in the months before his inauguration.
In what could be a dramatic shift in US foreign policy, officials acknowledged conversations with Trump regarding his approach to Russia will be “very difficult”.
Since winning the US election Mr Trump has used his first interviews to indicate that he will cut off support for rebel forces in Syria and thank the Russian president for sending him a “beautiful” letter.
But his views are highly contradictory to those of Theresa May, who last month called for Russia to be punished over its “sickening atrocities” in Aleppo, and has condemned Syrian president Bashar Al-Assad for inflicting “atrocious violence” on his people.
According to the Sunday Telegraph, Foreign Secretary Boris Johnson is expected to fly to the US within weeks to make clear to senior figures in Mr Trump’s administration that Britain believes President Assad must go.
Mr Johnson has accused Russia of committing war crimes over its bombing campaign in Aleppo.
Prime Minister Theresa May’s views on Russia are highly contrasted with the president-elect’s.
Foreign Secretary Boris Johnson will fly to the US to make clear Britain’s priorities in Syria.
Mr Trump used is first interview with the Wall Street journal to make clear that his administration will focus on defeating ISIS in Syria, rather than removing Al-Assad.
He said: “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.”
Foreign officials believe it will be “very difficult” to convince the president-elect to soften his stance on foreign policy, as he already has with several flagship plans such as his aim to repeal Obamacare.
An official told the Telegraph: “We have been very clear that Assad has no place in the future of Syria. He has the blood of 400,000 people on his hands.”
Another source said Mr Trump might change his position when he discovers Russian president Vladimir Putin is “not a rational or reasonable guy”.