Ukraine's Zelenskyy tells Congress: 'We are united ... the entire free world'

From the frontlines of the war in Ukraine to the political frontlines of Washington on Capitol Hill and the White House, Zelenskyy continues to take risks to defend Ukraine and show masterful skill at using language and symbolism to marshal international support.

"Remember Pearl Harbor. The morning of December 7, 1941, when your sky was black from the planes attacking you. Remember. Remember September 11. A terrible day in 2001 when people tried to turn your cities into battlefields. When innocent people were attacked from the air. No one expected it. You couldn't stop it," he said in his virtual speech to Congress in March.

"Our country experiences the same every day," he said.

Zelenskyy made an unannounced visit to the front-line city of Bakhmut on Monday, where Ukrainian and Russian forces have fought a months-long battle. The comedian-turned-politician who was elected to lead Ukraine in 2019, was named Time's person of the year earlier this month "for proving that courage can be as contagious as fear."

A U.S. official confirms to ABC News that Ukrainian President Volodymyr Zelenskyy has landed in the U.S

-ABC News' Sarah Kolinovsky

Secretary of State Antony Blinken formally announced the authorization of a $1 billion drawdown package for Ukraine. He added that the Department of Defense will provide an additional $850 million in security assistance, bringing the total of this latest influx to $1.85 billion.

That brings the administration's military support for Ukraine to an "unprecedented" total of $21.9 billion, Blinken noted.

The latest round of military support includes a Patriot missile defense system and precision bomb kits that will turn dumb bombs into smart bombs guided by GPS coordinates toward their targets.

More information about the new weapons systems being sent to Ukraine can be read here.

Blinken's announcement comes as Congress is working to pass a bill that would provide $45 billion more in military, economic and humanitarian assistance.

-ABC News' Shannon Crawford

Zelenskyy’s trip to Capitol Hill will be similar to State of the Union preparations because of the high-level nature of the address. Security officials at the most senior levels of government are "very" concerned about the prospect of something happening tonight, domestically or abroad, one source told ABC News.

According to an email sent to staff at the Capitol and obtained by ABC News, security measures will be "significant." The email says only staff and members will be allowed in the House wing past a certain time.

Another official said, “We are very cognizant that Russia has assets in this country and might try to do something. We know what is at stake.”

The source said the U.S. is aware that early on in the conflict the Russians apparently plotted to kill Zelenskyy. The official expressed concern that news of Zelensky’s visit broke so early about him coming to the United States. It would have been much better, he said, if our adversaries had less time, not more time, to think about doing something and to move assets and operatives around.

-ABC News Chief Justice Correspondent Pierre Thomas and Luke Barr