KYIV, Apr. 29 (Reuters) - President Volodymyr Zelenskiy said on Monday that vital U.S. weapons were starting to arrive in Ukraine in small amounts but deliveries needed to be faster as advancing Russian invasion forces were trying to take advantage.

Zelenskiy told a joint press conference in Kyiv alongside NATO Secretary-General 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.

The United States approved a $61 billion aid package last week, ending six months of congressional deadlock and raising Kyiv's hopes that its critically low stocks of artillery shells will soon be replenished.

Stoltenberg, who held talks with Zelenskiy during his third wartime visit to Kyiv, told Ukrainians that NATO members had failed to live up to their promises of military aid in recent months, but that the flow of arms and ammunition would increase.

"I will ... be very honest with President Zelenskiy and also with the Rada (Ukrainian parliament) that NATO allies have not delivered what we have promised over the last months," Stoltenberg said on the train taking him into Kyiv on Monday.

The NATO chief pointed to the U.S. aid bill and an announcement last week by British Prime Minister Rishi Sunak of a "record high" commitment to Kyiv.

He also noted Germany had agreed to provide another Patriot air defence system to Ukraine while the Netherlands had boosted its military aid to Kyiv. He said he expected other "new commitments to come".

"This will make a difference – as the lack of support made a difference," he said, alluding to Ukrainian setbacks on the battlefield over the past few months.

Russia has said a renewed influx of American weapons will not change the situation on front lines and that it will target storage sites holding Western weaponry in Ukraine.

Ukraine's top military commander said on Sunday his troops had pulled back from three villages in the east where Russian forces are on the offensive and gradually taking ground.

"The Russian army is now trying to take advantage of a situation when we are waiting for supplies from our partners... and that is exactly why the speed of deliveries means stabilising the front," Zelenskiy said.

"Russia is preparing for offensive actions."
The Ukrainian leader has repeatedly warned Russia might be planning a big offensive push in late May or in June.

Stoltenberg told reporters that it was "not too late for Ukraine to prevail.

"But that’s why it's so urgent that NATO allies now actually do what we had promised and that we turn those commitments into real deliveries of weapons and ammunition, and I’m now confident that will now happen," he said.

The Ukrainian leader singled out the need for supplies of sophisticated Patriot air defence launch systems that Kyiv wants to obtain from its allies to counter Russia's long-range missile and drone strikes.

Russia renewed its long-range aerial assault on the Ukrainian energy sector in March, inflicting heavy damage as Kyiv has lobbied its partners to rush in air defences to better protect its cities and critical infrastructure.

Zelenskiy said Kyiv had made some headway toward obtaining supplies of missiles for the Patriot system, but that it was still working on the question of obtaining new launchers that fire the missiles.

Photo from Reuters