With main battle tanks from the U.S. and Germany now headed to Ukraine, Kyiv is now focusing on securing modern fighter jets from Western allies.

Yuriy Sak, an adviser to Ukraine’s Defense secretary, told The Hill that he was optimistic about receiving Western fighter jets such as the American F-16s, which Ukrainians have sought since early last year when Russia first invaded.

“Every type of weapon we request, we needed yesterday,” Sak said. “We will do everything possible to ensure Ukraine gets fourth-generation fighter jets as soon as possible.”

Reuters first reported the news that Ukraine was setting its sights on fighter jets.

Ukraine scored a major win on Wednesday with the announcement from President Biden that the U.S. will donate 31 American-made M1 Abrams main battle tanks to Kyiv.

German Chancellor Olaf Scholz on Wednesday also said he would supply Ukraine with the country’s Leopard 2 tanks and approve the transfer of other Leopards from European allies.

The tanks were the latest hurdle for Western allies, who have cautiously approved more and more advanced weaponry for Kyiv, from HIMARS launchers to the Western battle tanks.

Western fighter jets and longer-range artillery units, which would allow Ukraine to strike Russian forces deeper in occupied territory, will likely be the next debate for NATO.

Ukraine currently uses Soviet-era fighter jets, including MiG-29s, which became a point of controversy last March when the U.S. declined to facilitate the transfer of MiGs from Poland to Kyiv.

So far, the U.S. has resisted sending the F-16 fighter jets and does not appear ready to announce their transfer anytime soon.

But national security adviser John Kirby told reporters on Wednesday the U.S. was “in constant discussions” with Ukraine and “we evolve those as the conditions change.”

“Can’t blame the Ukrainians for wanting more and more systems,” Kirby said. “It’s not the first time they’ve talked about fighter jets, but I don’t have any announcements to make on that front.”