Biden mirrored the warning Zelenskyy gave world leaders at the U.N. this week in a brief comment to reporters at the White House.

With Zelenskyy alongside him, Biden said that no nation would be secure if the world does not stand up to invaders. He said it was why the U.S. built a coalition to defend Ukraine and continues to work to formalize long-term commitments to the country.

He then applauded Zelenskyy for his leadership through the war.

"Your bravery has inspired the world," Biden said, adding that he was "determined to show" that "we stand with you."

Zelenskyy spoke briefly, thanking Biden and Congress, and noted that he had visited the 9/11 memorial with his wife, as "it's important to remember the victims of terrorism." Notably, Zelenskyy called Russia a "terrorist state" at the U.N. this week.

Biden and Zelenskyy said they would discuss weapons, with a particular focus on air defense systems. National security adviser Jake Sullivan and Secretary of State Antony Blinken joined them at the White House meeting.

A U.S. official shared a full list of the capabilities included in the next Ukraine security assistance package ahead of the announcement expected later today.

Valued at $325 million, it includes air defense capabilities, cluster munitions, anti-tank weapons and other equipment. It is the 47th tranche of equipment to be pulled from Pentagon inventories to aid Ukraine since August 2021.

The security assistance falls under the Presidential Drawdown Authority, which allows the president to pull military equipment from U.S. stocks and provide it to other nations. Biden is also asking Congress for $24 billion to sustain American support for Ukraine.

Capabilities in the package:

• AIM-9M missiles for air defense.
• Additional ammunition for High Mobility Artillery Rocket Systems (HIMARS).
• Avenger air defense systems.
• .50-caliber machine guns to counter Unmanned Aerial Systems.
• 155 mm artillery rounds, including Dual-Purpose Improved Conventional Munitions, or DPICM.
• 105 mm artillery rounds.
• Tube-Launched, Optically Tracked, Wire-Guided (TOW) missiles.
• Javelin and AT-4 anti-armor systems.
• Over 3 million rounds of small arms ammunition.
• 59 light tactical vehicles.
• Demolitions munitions for obstacle clearing,
• Spare parts, maintenance and other field equipment.

Biden and first lady Jill Biden welcomed Zelenskyy at the East Gate of the White House a little after 3:30 p.m.

It's the second time the Ukrainian president has come to visit the Bidens since the start of the war.

Zelenskyy arrived in a large SUV with his wife, Olena Zelenska, and then stood alongside the American president to pose for photos. He did not take any questions before entering the doors of the White House, flanked with a U.S. and a Ukrainian flag.

Zelenskyy's outreach on Capitol Hill appears to have been well received even by some lawmakers who are hesitant to provide additional funding to Ukraine.

Sen. Thom Tillis, R-N.C., criticized congressional Republicans who skipped the Ukrainian president's visit and applauded the wartime leader for laying out his argument for continued U.S. support.

"Make no mistake about it," he said, "anybody that could say this war would be over in 24 hours, or anybody who says we don’t need to support them because it’s not going to sustain the effort, is not paying attention to the details. It would be devastating."

Sen. Cynthia Lummis, R-Wyo., told NBC News that the Ukrainian president was asked how he would address American concerns that the U.S. is "getting into another forever war."

"I thought the way he answered that question, was his strongest answer," said Lummis, who has voted against Ukrainian aid in the past. "Because he made it clear that if Ukraine loses the war there will still be a 'forever war.'”

Zelenskyy argued that if Ukraine loses, there is a ceasefire or an agreed division of Ukrainian land, then Russia will not be deterred from invading other countries or restarting its war with Ukraine with greater firepower.

Lummis said his reasoning was "absolutely compelling" and "consistent with what we see on our own." Lummis added that while she still has concerns, she is now “convinced that we have to stay. We have to help Ukraine."

Two U.S. officials told NBC News that the next security package for Ukraine will amount to $325 million.

The package will include more air defense and artillery capabilities to support Ukraine's armed forces, Pentagon press secretary Pat Ryder told reporters at a briefing. The presidential drawdown will be the Biden administration's 47th tranche of equipment taken from the Department of Defense inventory.

This package is separate from the potential $24 billion military and humanitarian aid package that Biden has requested for Ukraine.

Pentagon press secretary Pat Ryder said the meeting between Secretary of Defense Lloyd Austin and Zelenskyy went well, describing it as "very warm" and "very engaging."

Few details about the two leaders' "great conversation" were shared by Ryder, but he emphasized the Ukrainian president's appreciation for the support of the U.S. and its people.

He also noted that "the secretary gave his personal commitment to stay engaged to work with our allies and partners to ensure that [Ukraine] have what they need."

Sen. Roger Marshall, R-Kan., who skipped a meeting with Zelenskyy earlier today, said he will not back sending any more U.S. money to Ukraine.

“At a time when our nation is facing a historic debt crisis, a wide-open southern border with fentanyl, Chinese military-aged nationalists, known terrorists, and cartels pouring into our country, I can’t even understand how this body can justify sending another blank check to Zelenskyy," Marshall said in a news release, adding that the U.S. is "hemorrhaging" money it can't afford while E.U. leaders stand idly by.

"There is no strategy, no exit plan, and no accountability from Zelenskyy," Marshall added. "My priority is securing our American homeland, not sitting through another charade."

Ukraine’s first lady, Olena Zelenska, said she was pleased to speak today at Georgetown University, which she called “a friend of Ukraine.”

She noted, however, that college students in her own country were fighting and dying as she spoke, and added that they, like the students at Georgetown, deserved an opportunity to study and read widely “instead of dying from bombs in the streets of their own cities.” Those opportunities is what they are fighting to defend, she said. 

“It’s a matter of survival. We want to live,” Zelenska said. “That is why you fight and hold on as long as possible — to have a chance at life.”

The first lady answered several questions from Ambassador Melanne Verveer, the executive director of the Georgetown Institute for Women, Peace and Security, and one from a Ukrainian student who is studying at Georgetown. 

Her answers touched on Ukrainian resilience, female leadership, gender inequality, and her country’s need for humanitarian and health care support. She also discussed the work of her foundation, which is directed toward addressing mental health and aiding children in Ukraine. 

Verveer and Georgetown University President John DeGioia also presented the Ukrainian first lady with the Hillary Clinton Award for Advancing Women Women in Peace and Security. She was given the honor last year but was unable to leave Kyiv for the award ceremony at the time.