Rishi Sunak will call on world leaders to ensure a “lasting peace” for Ukraine with the establishment of a new Nato charter to help the country defend itself “again and again” in the face of any future declarations of war by Russia. Fresh from hosting the Ukrainian president, Volodymyr Zelenskiy, in the UK last week, Sunak is expected to call for countries to “double down on our military support” and warn that “the security and sovereignty of every nation” is at stake. He will mark the approaching one-year anniversary of the Kremlin’s invasion of Ukraine by attending the Munich Security Conference, and urge fellow premiers not to “lose our nerve” in upholding sanctions and providing military kit. Keir Starmer, the Labour leader, was also due to speak at the conference, but strikes at Munich airport meant a planned flight from Poland to Germany was cancelled. He had been in Ukraine, visiting Zelenskiy to affirm that a Labour government would be unwavering in its support for Kyiv. Starmer’s space on a panel will be filled instead by David Lammy, the shadow foreign secretary, while the shadow defence secretary, John Healey, is also at the conference. Although Sunak will use the sidelines of the security conference to speak to EU leaders about talk of an imminent breakthrough on post-Brexit trading arrangements in Northern Ireland, his main objective will be maintaining western unity against Russia. “Now is the moment to double down on our military support,” the prime minister is expected to say. “When [Vladimir] Putin started this war, he gambled that our resolve would falter. Even now he is betting we will lose our nerve. But we proved him wrong then, and we will prove him wrong now.” Pushing for a new Nato charter to protect Ukraine from future Russian aggression, he is expected to say: “We must demonstrate that we’ll remain by their side, willing and able to help them defend their country again and again.” Last year, the UK provided military aid worth £2.3bn, including tanks, other armoured vehicles, and anti-tank missiles. No 10 has committed to matching or exceeding that level of support in 2023. A minute’s silence will be held at 11am on Friday 24 February to mark the anniversary of the invasion of Ukraine.