A trip planned by US Secretary of State Rex Tillerson will still go ahead later in the week, with Mr Johnson leading efforts to bring together a coalition against Russian action in Syria and the regime of Syrian President Bashar al-Assad.
Mr Johnson discussed the move with his US counterpart last night as the world reacted to the launch of 59 tomahawk cruise missiles targeting the Shayrat airbase, following intelligence that deadly chemical weapons attacks on civilians originated there.
Military and diplomatic experts told The Independent the attack had created an opportunity to lever Moscow into a position better suited to negotiating peace in Syria.
In a statement, Mr Johnson said: “Developments in Syria have changed the situation fundamentally. My priority is now to continue contact with the US and others in the run up to the G7 meeting on 10 and 11 April, to build coordinated international support for a ceasefire on the ground and an intensified political process. I will be working to arrange for other like-minded partners to meet and explore next steps soon too.
“I discussed these plans in detail with Secretary Tillerson. He will visit Moscow as planned and, following the G7 meeting, will be able to deliver that clear and coordinated message to the Russians.
“We deplore Russia’s continued defence of the Assad regime even after the chemical weapons attack on innocent civilians. We call on Russia to do everything possible to bring about a political settlement in Syria and work with the rest of the international community to ensure that the shocking events of the last week are never repeated.”
Sources said Mr Johnson was “relaxed” about who delivers the West's message to Moscow next week following the air strikes, while there was concern on both sides of the Atlantic that two trips a few days apart may allow the Russians to “split hairs”.
London and Washington agreed that while Mr Tillerson would head into meetings with his Russian counterpart Sergei Lavrov, Mr Johnson will drum up support among G7 nations to address Russia's actions in Syria ahead of Tuesday's meeting of the group.
He will push for counterparts to adopt goals, including a transition away from Assad in Syria, Russia demilitarisation in the country and plans to rebuild infrastructure alongside any peace deal.
On Friday US envoy to the UN, Nikki Haley, said America was “prepared to do more if necessary” and would not stand by while chemical weapons were used, while the Pentagon said it was investigating whether Russia took part in the chemical attacks that killed up to 100 civilians in Idlib on Tuesday.
The UK Government said it “fully supported” President Trump’s action, though Russian Prime Minister Dmitry Medvedev warned the US strike came “within an inch” of sparking military clashes with his country’s forces.
Former head of the British Army Richard Dannatt told The Independent the US missile strikes against the Assad regime could provide an opportunity to push Russia towards a negotiated peace in Syria.
He said: "It actually shows that the world’s most powerful country and most economically successful country is willing to show a bit of leadership...Diplomacy is always better when it is backed up by strength. The velvet glove needs to have an iron fist within it.
“So I don’t think this should take us in to further military activity inevitably, but should take us more enthusiastically to Geneva around the conference table."