Washington(CNN) Ukrainian President Volodymyr Zelensky will deliver a speech to members of the US Congress on Wednesday, marking a rare moment for the Eastern European leader to address American lawmakers as his country continues to fight against the Russian invasion.
The speech follows Zelensky's similar virtual addresses to other NATO allies, during which the Ukrainian leader has called on the West to aggressively ramp up its efforts to counter Russia's shelling of Ukrainian territory.
Zelensky's remarks will take place the day after President Joe Biden signed a massive spending bill into law, which includes more than $13 billion in Ukraine aid.
Zelensky, who remains in Ukraine, will address members of Congress at 9 a.m. ET on Wednesday. Here's what to watch for:
Zelensky is expected to renew his calls for more weapons, as well as a no-fly zone over Ukraine, during the address.
The Ukrainian leader has pressured Biden officials to help broker the transfer of Soviet-made weaponry to his country, including MiG fighter jets and S-300 surface-to-air missile systems.
The Biden administration has so far not helped provide those weapons systems. US officials, including Biden, continue to have concerns that Russia might perceive such a weapons transfer as an escalation in hostilities.
Ahead of Wednesday's remarks, top House and Senate Republicans sent a letter calling on the Biden administration to provide Ukraine with Soviet- and Russian-made air defense systems to help defend against the invasion.
Zelensky has been pressuring Biden and NATO to do more, expressing frustrations over Western allies' concerns about provoking Russian President Vladimir Putin.
On Tuesday, Zelensky called Article 5, the principle that enshrines that an attack on one NATO country is considered an attack on all NATO countries, "weak."
"Some states of (the) alliance have intimidated themselves, saying that they can't answer. That they cannot collide with Russian missiles and planes in the Ukrainian sky. Because this, they say, will lead to escalation, will lead to the third world war. ... And what will they say if Russia goes further to Europe, attacking other countries? I am sure the same thing they say to Ukraine," he said. "Article 5 of the NATO treaty has never been as weak as it is now. This is just our opinion."
Zelensky may use his platform with Washington to make a specific appeal to the lawmakers in the room and the Americans watching at home.
In a speech earlier this month to the UK's House of Commons, Zelensky received a standing ovation when he referenced wartime Prime Minister Winston Churchill's most famous speech.
"We will not give up and we will not lose. We will fight until the end at sea, in the air. We will continue fighting for our land, whatever the cost," Zelensky said.
And in a speech to Canada's Parliament on Tuesday, he asked lawmakers to imagine how they would react to an invasion of their own cities.
"Can you only imagine that on 4 a.m., you start hearing bomb explosions, severe explosions? Can you imagine hearing your children, hear all of these severe explosions? Bombing of airport? Bombing of Ottawa airport? Tens of other cities of your wonderful country -- can you imagine that?" he said.
He continued the analogy: "Can you imagine the famous CN Tower in Toronto, if it was hit by Russian bombs? Of course I don't wish this on anyone, but this is our reality in which we live."
Zelensky may call on lawmakers to move forward on harsher sanctions against Russia.
During his most recent call with Biden, Zelensky pressed the US to implement further sanctions against Russia, in an effort to cut the country off from international trade and target the Russian elite.
The House has passed largely symbolic legislation banning the imports of Russian oil and limiting Russia's access to the World Trade Organization, which followed Biden's executive order banning Russian energy imports. House Speaker Nancy Pelosi said this week that the House intends to take up legislation to revoke Russia's trade status as a "most favored nation" -- a move backed by Biden that requires an act of Congress.
Top Republicans in recent weeks purposefully measured their criticism of Biden, signaling that they want to put on a united front and send a clear signal that the President would have bipartisan support if he were to move ahead with more punitive measures.
More than 3 million people have fled Ukraine since the start of the Russian invasion on February 24, the International Organization for Migration said Tuesday.
Nations across Europe have continued to see an increase in Ukrainian refugees entering their countries, with more than 1.8 million Ukrainians crossing into Poland's territory as of Tuesday, according to United Nations High Commissioner for Refugees data.
US Secretary of State Tony Blinken on Tuesday announced $186 million in additional humanitarian assistance to support Ukrainian refugees and internally displaced people due to the war in Ukraine. Vice President Kamala Harris has said the US was willing to take in more migrants. And the Biden administration is considering expediting the resettlement of Ukrainian refugees with US ties, including family already living here, according to a US official.
But border policies leaving thousands of migrants and refugees from other nations in limbo also kept out a Ukrainian family fleeing the war. A Ukrainian woman and her three children crossed into the US on Thursday after being turned away at the US-Mexico border a day earlier, according to the family's attorney.
In the hours after Zelensky's speech to Congress, Biden is slated to deliver a speech demonstrating the support the US is providing to Ukraine.
Biden is expected to announce an additional $800 million in security assistance, according to an official — bringing the total announced in just the last week to $1 billion and $2 billion since the beginning of the Biden administration.
He will unveil the new package of military assistance, including anti-tank missiles, as soon as that speech, according to officials familiar with the plans.
The new assistance will stop short of the no-fly zone or fighter jets Zelensky has said are necessary to sustain Ukraine's fight against Russia. But the new aid will include more of the defensive weapons the US has already been providing, including Javelins and Stingers.
The Wall Street Journal first reported the anticipated assistance announcement.
The speech will come a day after the President signed a spending bill into law that dedicates $13.6 billion in aid to Ukraine.
Speaking on CNN on Tuesday, Deputy Secretary of State Wendy Sherman said the President would talk "about the security assistance that we have provided, that we are providing. It's just unparalleled in amounts. Anti-tank, anti-aircraft, anti-armor, all kinds of support that the Ukrainians have asked for."
Next week, Biden will travel to Europe to meet with NATO leaders and attend a European Council summit to discuss the Ukraine war.