Speaking after taking part in calls with European leaders and US President Donald Trump about the war in Ukraine, Vance said the US troops' presence was essential to helping to end the fighting.

Trump is to meet with Russian President Vladimir Putin on Friday in Alaska "to try to achieve an end to this terrible war in Russia and Ukraine", Vance told US troops stationed at the UK's air force base in Fairford, Gloucestershire in southwest England.

"You guys make that possible. You guys are the reason why we can go into a negotiation with strength," Vance said.

"Nothing that we do as an administration is possible without the hard work, the courage and the skill that you guys bring to the job," he added.

He addressed the troops after calls with Trump and European leaders ahead of the Alaska summit, aimed at convincing the US leader to respect Kyiv's interests in the talks.

British Prime Minister Keir Starmer said Wednesday that there was now a "viable" chance for a ceasefire after over three years since Russia's February 2023 invasion of Ukraine.

Vance arrived in the UK on August 8 with his wife and three children, only to be met by protests from residents in the Cotswolds countryside.

He has spent much of his time in meetings with UK officials, including Foreign Secretary David Lammy, who hosted Vance at his country retreat in Chevening in Kent, southeast of London over the weekend.

On Wednesday, Vance reportedly had breakfast with Nigel Farage, leader of the anti-immigrant Reform UK party, which is topping the current electoral polls.

He met late Tuesday with Conservative Party justice spokesman Robert Jenrick, but has not managed to schedule face-to-face talks with the Tory leader Kemi Badenoch, The Times newspaper reported.

Vance is reportedly heading next to Scotland with his family for several days.