The UK has promised £3bn a year “for as long as it is necessary” to help Ukraine, David Cameron said on Thursday as he made his second visit to Kyiv since becoming UK foreign secretary. He also said he had no objection if weapons supplied by the UK were used to strike inside Russia. Lord Cameron – who met the Ukrainian president, Volodymyr Zelenskiy, and the foreign minister, Dmytro Kuleba, on his trip – has made securing extra arms for Ukraine one of his top priorities as foreign secretary. His announcement is the UK’s biggest spending pledge since Russia’s full-scale invasion in 2022. In January the UK prime minister, Rishi Sunak, pledged £2.5bn in military aid to Ukraine for 2024-25, an increase of £200m on the previous two years. He gave no commitment beyond that date. Cameron said in a Reuters interview: “Ukraine has the right to strike inside Russia because Russia is striking inside Ukraine … You can understand why Ukraine feels the need to defend itself.” He added: “We’ve just emptied all we can in terms of giving equipment. Some of the equipment is actually arriving in Ukraine today while I am here.” The foreign secretary announced that the UK’s donation of military equipment would include precision-guided bombs, air defence missiles and equipment for 100 mobile air defence teams to enable Ukraine to shoot down Russia’s drones and missiles. The UK also committed to doubling its domestic munitions production by investing a further £10bn over the next 10 years. This production aims to ensure UK national security while sustaining the flow of weapons to Kyiv, keeping Ukraine in the fight for as long as it takes. Cameron said the UK would bring international partners together next month to attract additional contributions to the International Fund for Ukraine to meet Ukraine’s urgent capability requirements. The foreign secretary also confirmed a £36m package for Ukraine’s energy infrastructure, and investment in future innovations to support Ukraine’s energy transition and recovery. Cameron said: “Ukraine is fiercely defending itself against Russia’s illegal invasion, making a war Putin thought would last days take years. But this war is the challenge of our generation and Ukraine cannot fight it alone. “We must all step up to ensure Ukraine has what it needs to win. Through our multi-year military funding, weapons provision and vital support to protect and repair Ukraine’s energy infrastructure, the UK is standing with Ukraine and we will stand with Ukraine for as long as it takes.” Cameron has ruled out sending British troops to Ukraine, but in an interview with the Economist, the French president, Emmanuel Macron, maintained his stance of strategic ambiguity, saying: “I’m not ruling anything out, because we are facing someone who is not ruling anything out. We have undoubtedly been too hesitant by defining the limits of our action to someone who no longer has any and who is the aggressor. “Our capacity is to be credible, to continue to help, to give Ukraine the means to resist. But our credibility also depends on a capacity to deter by not giving full visibility as to what we will or will not do. Otherwise we weaken ourselves.” If the Conservatives are not re-elected a Labour government would either have to adopt Cameron’s spending commitment or renounce it. The UK’s Ukraine policy has generally been agreed on a broadly bipartisan basis but it is not known if this multi-year pledge to continue arming Ukraine’s military for “as long as it takes” was cleared with the Labour leader, Keir Starmer, in advance.