Ukraine’s ambassador to the United States asked Washington to rush air defense weapons to the embattled Eastern European country — but did not mention Polish fighter jets or explicitly call for a no-fly zone, a probable preview of her president’s rare virtual address to Congress on Wednesday.

“Any type of weapons that we can receive with a special focus on anti-air and everything to stop their dominance in the air,” said Ukrainian Ambassador Oksana Markarova, referring to Russian attacks, in remarks at the National Press Club on Tuesday. “Air is something that we need urgent support with. Protect Ukraine from the brutal attacks they are doing from the air.”

Markarova, who has served as ambassador for nearly a year, said Ukraine needed an “immediate increase in military support in order to be able to stay in this fight.”

Over the weekend, the State Department announced a fourth presidential drawdown of as much as $200 million in new military assistance to Ukraine, bringing total security assistance provided since the start of the Biden administration to over $1.2 billion. Drawdown authority permits the president in emergency situations to direct weapons, ammunition and other material from U.S. military stockpiles to partner nations.

What’s more, President Joe Biden on Tuesday signed a fiscal 2022 omnibus spending package, that includes $3.5 billion in emergency funding to replenish U.S. military stockpiles for equipment sent to Ukraine through presidential drawdowns. There’s also an additional $650 million in State Department-administered Foreign Military Financing grants for Kyiv to use to buy American-made weapons.

But despite the hundreds of millions of dollars in security assistance heading Ukraine’s way, Kyiv wants the West to ramp up its military support, specifically by providing fighter jets that Ukrainian pilots can use against the invading Russians.

A burgeoning plan — popular with Republicans and many Democrats on Capitol Hill — for Poland to transfer its Soviet-era MiG fighter jets to U.S. military custody so they could be given to the Ukrainians fell apart after the Biden administration concluded the potential heights of an escalation with Russia outweighed any military benefits the planes would provide to Ukraine.

Instead, some defense analysts have argued, the United States should focus on giving Ukraine other types of air defense systems that are better bang for the buck, such as man-portable air defense systems (MANPADs), counter-artillery radar and surface-to-air missiles.

“We’re going to continue to get as much security assistance to the Ukrainians as fast as we can,” using the most efficient way possible, Pentagon spokesman John Kirby told reporters Monday.

Likewise, Kyiv’s calls for the United States and other NATO countries to establish a no-fly-zone over parts or all of Ukraine have failed to gain traction with the Biden administration. Enforcing an NFZ would likely entail the shooting down of Russian fighter planes, which would put the United States in direct military conflict with Russia — something the two nuclear powers managed to avoid even during the worst moments of the Cold War.

Ukrainian President Volodymyr Zelenskyy on Wednesday morning will become the first foreign head of state to address Congress via a “virtual address,” broadcast for members into the Capitol Visitor Center Congressional Auditorium. If he renews calls for the U.S. to provide Ukraine with fighter planes or to establish an NFZ, it will put the White House in an awkward position. It also will do the same for those Democrats on the Hill sympathetic to administration officials’ reasoning about wanting to limit the risks of military escalation, including nuclear, with Moscow.

Since Russia’s invasion of Ukraine nearly three weeks ago, U.S. lawmakers have rallied around Zelenskyy, finding inspiration from his wartime example of remaining in Kyiv in order to provide moral support for his countrymen as they continue to mount a surprisingly resilient and potent response to Russia’s invading forces.

Since the Kremlin began ramping up its invasion threats several months ago, Markarova has become one of the most in-demand figures in Washington. She regularly meets and communicates with senators and lawmakers and was first lady Jill Biden’s guest at the State of the Union address earlier this month.

Speaking at the Press Club, Markarova, who previously served as Ukraine’s finance minister, called for the U.S. and other partner countries to use “all of the diplomatic power that the world can put together in order to force Russia to allow the humanitarian corridors, which they’ve denied us.”

And she urged more sanctions.

“We have to isolate Russia completely,” the ambassador said.

On Tuesday, the Treasury and State departments announced a new round of targeted sanctions on 11 top Russian military officials and the autocratic ruler of Belarus, Alyaksandr Lukashenka, his wife, Galina, and their adult sons.

Internationally, the European Union on Tuesday formally adopted new sanctions that ban investments in Russia’s energy sector and prohibit imports of Russian steel. And the United Kingdom announced it was revoking “most favored nation” trade status for Russia and Belarus, which will result in the loss of favorable tariffs for hundreds of their exports, according to a daily sanctions roundup compiled by the K2 Integrity risk analysis firm.

Andrew Clevenger contributed to this report.