British Prime Minister Rishi Sunak on Saturday pledged to provide Challenger 2 tanks to Ukraine, making it the first Western country to supply the heavy tanks Kyiv has been calling for.The pledge saw a swift reaction from Russia which warned it would only "intensify" the conflict."Bringing tanks to the conflict zone, far from drawing the hostilities to a close, will only serve to intensify combat operations, generating more casualties, including among the civilian population," the Russian embassy in London said.Sunak said the tanks were a sign of the U.K.'s "ambition to intensify our support to Ukraine", according to a readout of a phone call with Ukrainian President Volodymyr Zelensky.Ukraine's European allies have sent Kyiv more than 300 modernized Soviet tanks since Russia invaded in February 2022.But they have so far held off on dispatching the Western-made heavy tanks that Ukraine has repeatedly requested.Zelensky thanked the U.K.

on Twitter for making decisions that "will not only strengthen us on the battle field, but also send the right signal to other partners".Ukraine's forces have taken heavy losses in the battles of Soledar and Bakhmut in recent months and have called on the country's allies to give it more support.Russia said on Friday its forces had wrested control of the war-scarred town of Soledar in east Ukraine, its first claim of victory in months of battlefield setbacks, although Ukraine said fierce fighting was still underway. "To win this war, we need more military equipment, heavy equipment," Andriy Yermak, head of Ukraine's presidential office, said.Foreign Minister Dmytro Kuleba also said that he had spoken with U.S.

Secretary of State Antony Blinken and "emphasized the need" for Ukraine to receive Western-type tanks.Sunak's formal offer follows reports that he was preparing to sign off on sending four British Army Challenger 2 main battle tanks to eastern Europe immediately, with eight more to follow shortly afterward.The prime minister's office has not yet confirmed the exact number of tanks it will send to Kyiv.A Downing Street spokesman said Sunak and Zelensky agreed on the "need to seize on this moment" after Ukrainian victories had "pushed Russian troops back.""The Prime Minister outlined the U.K.'s ambition to intensify our support to Ukraine, including through the provision of Challenger 2 tanks and additional artillery systems," the spokesperson said.The issue of heavy tanks has long been a key one for Kyiv and many experts see providing Ukraine with modern tanks as a vital building block in its ability to win against Russia.Germany remains fearful of escalation from Moscow and has been especially hesitant of supplying heavy tanks, though it has already delivered powerful mobile artillery and air defenses. The Downing Street spokesperson added that Sunak and Zelensky "welcomed other international commitments including Poland's offer to provide a company of Leopard tanks.""The Prime Minister stressed that he and the whole U.K.

government would be working intensively with international partners to deliver rapidly the kind of support which will allow Ukraine to press their advantage, win this war and secure a lasting peace," he said.The U.K.

announcement comes ahead of next week's meeting of the Ukraine Defence Contact Group, which coordinates arms supplies to Kyiv, at Ramstein Air Base in Germany.