KYIV (Reuters) - President Volodymyr Zelenskiy said on Monday that vital U.S. weapons were starting to arrive in Ukraine in small amounts and that the process needed to move faster as advancing Russian forces were trying to take advantage.

Zelenskiy told a joint news conference in Kyiv alongside visiting NATO chief Jens Stoltenberg that the situation on the battlefield directly depended on the speed of ammunition supplies to Ukraine.

"Timely support for our army. Today I don't see anything positive on this point yet. There are supplies, they have slightly begun, this process needs to be sped up," he said.

(Reporting by Pavel Polityuk; writing by Tom Balmforth; editing by Ed Osmond)