LONDON -- British Prime Minister Keir Starmer announced on Sunday that Britain will allow Ukraine to use 1.6 billion pounds ($2 billion) of British export finance to purchase more than 5,000 air defense missiles.

"This will be vital for protecting critical infrastructure and strengthening Ukraine," Starmer told a press conference following a summit with Western leaders in London.

The goal is "to put Ukraine in the strongest position" so the country can negotiate from a position of strength, he added.

Western leaders, including more than a dozen European heads of state and Canadian Prime Minister Justin Trudeau, gathered in London on Sunday for a defense summit aimed at advancing a peace plan for Ukraine.

Starmer said leaders at the summit had agreed on a four-step plan to guarantee peace in Ukraine: to maintain military aid to Ukraine while the conflict continues and increase economic pressure on Russia; to ensure that any lasting peace guarantees Ukraine's sovereignty and security, with Ukraine at the table for any negotiations; to deter "any future invasion by Russia" in the event of a peace deal; and to establish a "coalition of the willing" to defend Ukraine and uphold peace in the country.

The leaders also agreed to meet again soon to sustain the momentum behind these efforts, Starmer said.

The prime minister reaffirmed Britain's commitment to supporting the peace plan with "boots on the ground, and planes in the air."

"Europe must do the heavy lifting," he said, emphasizing that the agreement needs US backing.

"Let me be clear, we agree with Trump on the urgent need for a durable peace. Now we need to deliver together," he said.

Earlier on Sunday before the summit, Starmer announced that Britain, France and Ukraine will work on a ceasefire plan to present to the United States. He named three essential points to achieve "lasting peace" — a strong Ukraine, a European element with security guarantees, and a US backstop, with the last one being the subject of "intense" discussion.

The summit took place amid diplomatic tensions, following a heated exchange earlier this week between Ukrainian President Volodymyr Zelensky and US President Donald Trump at the White House, which led to the cancellation of an anticipated raw materials agreement between the two countries.

On Saturday, Zelensky met with Starmer at 10 Downing Street, where the British prime minister reaffirmed the UK's "unwavering determination" to achieve lasting peace in Ukraine. Following the meeting, Ukrainian Finance Minister Serhiy Marchenko announced that Britain and Ukraine had agreed on a loan of 2.26 billion pounds to support Ukraine's defense capabilities.