President Volodymyr Zelenskyy has said that vital US weapons have started to arrive in Ukraine in small amounts, but that deliveries need to be faster as Russian forces continue to advance on the battlefield.

Zelenskyy told a joint press conference in Kyiv alongside NATO Secretary-General Jens Stoltenberg on Monday 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.

Last week, the United States approved a $61bn aid package, ending six months of congressional deadlock and raising Kyiv’s hopes that its critically low stocks of artillery shells will soon be replenished as it fights off Russia’s two-year invasion.

Stoltenberg told Ukrainians that NATO members had failed to live up to their promises of military aid in recent months.

“Serious delays in support have meant serious consequences on the battlefield” for Ukraine, he said.

“The lack of ammunition has allowed the Russians to push forward along the front line. Lack of air defence has made it possible for more Russian missiles to hit their targets, and the lack of deep strike capabilities has made it possible for the Russians to concentrate more forces,” Stoltenberg said.

Earlier, he said that the flow of arms and ammunition would increase, pointing to the US aid bill and an announcement last week by British Prime Minister Rishi Sunak of a “record high” commitment to Kyiv.

He noted that 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.

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

Odesa strike

Russia continues to launch missiles, drones and bombs at cities across Ukraine.

At least four people were killed and 27 injured in a Russian missile strike on residential buildings and “civil infrastructure” in the Ukrainian port city of Odesa on Monday, regional governor Oleh Kiper said on the Telegram messaging site.

Drawn-out Ukrainian efforts to mobilise more troops, and the belated building of battlefield fortifications, are other factors undermining Ukraine’s war effort, military analysts say.

Nick Reynolds, a research fellow for land warfare at the London-based Royal United Services Institute, said the war “is still largely an artillery duel”.

He said he did not expect to see major movement of the front lines in the near term, but that “the conditions are being set for which side has military advantage at the front line … [and] the Russian military is in a better position at the moment.

“When we see one side or the other being in a position to move the front line, at some stage, manoeuvre will be restored to the battlefield,” Reynolds told the Associated Press news agency.

“Not in the next few weeks, maybe not even in the next few months. But it will happen.”