NATO Secretary General Jens Stoltenberg called on NATO member states to supply more weapons to Ukraine, according to an interview published on Friday.
"I call on allies to do more. It is in all our security interests to make sure Ukraine prevails and (Russian President Vladimir) Putin does not win," Stoltenberg told German news agency dpa.
He said it was perhaps even more important that Ukraine receive enough ammunition for the systems already in place, adding that the need for ammunition and spare parts was "enormous".
Last week, Ukrainian President Volodymyr Zelenskiy in an address to a group of Western leaders asked for a wide range of weapons and air defense systems to help efforts to counter the Russian invasion.
Also, the United States last week announced nearly $2 billion in additional military aid, including the Patriot Air Defense System, which offers protection against aircraft, cruise and ballistic missiles.
Stoltenberg told dpa that military support for Ukraine was the fastest way to peace.
"We know that most wars end at the negotiating table - probably this war too - but we know that what Ukraine can achieve in these negotiations depends inextricably on the military situation," he said.
Russia invaded Ukraine on Feb. 24 in what Putin calls a "special military operation" against what he perceives as threats to Russian security.
Ukraine and its Western allies have denounced Russia's actions as an imperialist-style land grab and imposed sanctions to try to disrupt the campaign.
The 11-month war has killed tens of thousands of people, driven millions from their homes, left cities in ruins and shaken the global economy, driving up energy and food prices.