Ukraine has repeated a call to Western leaders to supply Kyiv with advanced weapons to fight Moscow's slowly advancing troops, one month after their invasion.

"Our armed forces and citizens are holding out with superhuman courage, but we cannot win a war without offensive weapons, without medium-range missiles that can be a means of deterrence," Ukrainian Presidential advisory Andriy Yermak said during a panel discussion late Tuesday.

"In our case, deterrence, not aggression," he added.

The appeal comes shortly after Russia announced it had deployed hypersonic missiles on the battlefield, close to Ukraine's border with NATO member Romania, in what analysts said was the first use of such weapons in the world.

Yermak said it was "impossible" for Ukraine to effectively defend itself without a reliable "air defence system that shoots down enemy and ballistic missiles from a great distance."

Biden and other NATO leaders have been stepping up military support for Ukraine including anti-tank weapons that have helped to stall Russian forces.

Ukraine's appeal for greater military support from Western allies has been a key refrain in a spate for recent addresses by President Volodymyr Zelensky to European and Western lawmakers.

Zelensky was due to address Japanese and French lawmakers Wednesday, and a special NATO summit Thursday. The Ukraine leader recently conceded Kyiv was not likely to become a member of the bloc.

"They don't want to see us in NATO. This fear of escalation is understandable. But it will not save us," Yermak added in his address Tuesday.