Will U.S. aid arrive in time for Ukraine's fight against Russia's army?

The renewed support comes ahead of an expected Russian offensive, which Zelenskyy himself has said could happen as early as this summer. Moscow’s forces have already been pushing in several directions in recent weeks, raising the specter of a possible attack on Ukraine’s second-largest city, Kharkiv.

Russia’s defense ministry said its troops claimed two villages in the eastern Donetsk region in as many days this week, as the Kremlin looks to exploit beleaguered Ukrainian defenses and make as many gains as possible before the new aid arrives.

“If I were Gerasimov, I’d be pushing forwards as much as I could while there was a window of opportunity,” said Matthew Ford, associate professor in war studies at the Swedish Defence University in Stockholm, referring to Russian army chief Valery Gerasimov.

Bohdanivka, the village claimed by Russia on Sunday, lies just over 3 miles east of the town of Chasiv Yar, a heavily fortified base for the Ukrainian army. Ukraine’s top commander said last week that Russian forces were aiming to capture the town by May 9, a symbolic date when Russia celebrates the Soviet victory over Nazi Germany.

“Russia has the initiative on the battlefield. In the short term, that’s unlikely to be affected by the U.S. release of weapons to Ukraine,” Ford said. “Systems that help with air defense will help protect critical infrastructure. However, it is unlikely that land systems will challenge the current tempo of Russian activity as the summer fighting season starts.”

In Ukraine, there was mixed opinion about the new aid and what difference it could make on the battlefield.

“As long as Ukraine is continuing its fight, nothing is too late,” Dmytro Pletenchuk, the spokesman for Ukraine’s southern military command, told NBC News, adding that the show of support after months of uncertainty and arguments would help boost the morale of troops and civilians behind the front lines, because they know “the civilized world is behind us.”

A Ukrainian drone pilot serving in the Kharkiv region also told NBC News that he welcomed the news, as drone units had been forced to cover for artillery units dealing with a severe shortage of shells. “We see this very positively,” said the soldier, who goes by the call-sign “Amida” and did not want his name used because he was not authorized to speak to the media.