"This support is essential. Ukraine needs more, because a promise of help does not end the war," the alliance secretary general told a ceremony at NATO headquarters. "Ukraine needs ammunition today and every day until the bloodshed stops."

Standing alongside Ukraine's ambassador to the alliance, Alyona Getmanchuk, Rutte said Western support was "imperative" to enable Ukraine to "defend itself against Russian terror from the sky and to hold the front lines".

Getmanchuk told diplomats and military officers from NATO's 32 member states "every additional air?defence system, every delivery of ammunition, every interceptor missile not only saves lives -- it strengthens Ukraine's position at the negotiating table."

As the so-called "Coalition of the Willing" supporting Kyiv prepared to meet Tuesday to mark four years since the invasion, Rutte reiterated the conditions for a "lasting" peace.

"When the fighting eventually stops, the peace has to halt with strong Ukrainian forces ready to deter and defend, and effective security guarantees from Ukraine's partners -- Europe, Canada and the United States," Rutte said.

"There cannot be true peace in Europe without real peace in Ukraine," he said. "This has been a bleak winter for Ukraine, but there is hope and help at hand."