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Zelensky delivers impassioned plea for more help fighting Russia on the 'frontline of tyranny'

(CNN) Ukrainian President Volodymyr Zelensky delivered a historic speech from the United States Capitol Wednesday night, expressing gratitude for American support in fighting Russian aggression since the war began -- and asking for more.

"I hope my words of respect and gratitude resonate in each American heart," Zelensky said during the joint meeting of Congress, later adding, "Against all odds, and doom and gloom scenarios, Ukraine didn't fall. Ukraine is alive and kicking."

But alongside Zelensky's gratitude was a plea, emphasizing that his armed forces are outnumbered and outgunned by the Russian military even as they fight on. At one point, Zelensky drew laughs from the chamber when he said, "We have artillery, yes. Thank you. We have it. Is it enough? Honestly, not really."

Zelensky's visit to Washington marks his first trip outside his homeland since it was invaded 300 days ago, arriving Wednesday afternoon to set a course for the future of the war alongside a key Western ally.

On "the frontline of tyranny," Zelensky argued during his speech to Congress, American support "is crucial not just to stand in such (a) fight but to get to the turning point to win on the battlefield."

"The world is too interconnected and too interdependent to allow someone to stay aside and at the same time to feel safe when such a battle continues," he added. "Our two nations are allies in this battle and next year will be a turning point, I know it -- the point where Ukrainian courage and American resolve must guarantee the future of our common freedom, the freedom of people who stand for their values."

"Your money is not charity," he asserted to Congress. "It's an investment in the global security and democracy that we handle in the most responsible way." Zelensky also called on lawmakers to strengthen sanctions against Russia.

Still, despite that disparity in resources, Zelensky said, "Ukraine holds its line and will never surrender."

In his speech, Zelensky harkened back to American history, referencing the Battle of the Bulge, President Franklin D. Roosevelt and the Battle of Saratoga. Just like "brave American soldiers which held their lines" and fought against Adolf Hitler's Nazi Germany in 1944, Ukrainian soldiers "are doing the same to Putin's forces this Christmas," Zelensky said.

He also briefly discussed a 10-point peace formula and summit that he told US President Joe Biden about during an earlier meeting at the White House. Zelensky claimed Biden supported the peace initiatives.

Zelensky also recalled his recent visit to the frontlines -- Bakhmut in Donbas -- which has been under siege since May. There, he said, "every inch of that land is soaked in blood, roaring guns sound every hour." In the climatic moment of the speech, he unveiled a Ukrainian flag signed by soldiers fighting in Bakhmut that he gave as a gift to the Congress.

"The occupiers have a significant advantage in artillery. They have an advantage in ammunition. They have much more missiles and planes than we ever have. It's true, but our defense forces stand," he added.

Russia, Zelensky argued in strong terms, has "found an ally" in Iran.

"Iran's deadly drones sent to Russia in hundreds became a threat to our critical infrastructure. That is how one terrorist has found the other," he said. "It is just a matter of time when they will strike against your other allies if we do not stop them now."

Zelensky's White House visit

Earlier Wednesday the Ukrainian leader visited the White House, where he met with Biden and held a joint news conference, during which the duo displayed a united front on their approach to the war.

"I think ... we share the exact same vision, and that a free, independent, prosperous and secure Ukraine is the vision -- we both want this war to end," Biden told reporters in the White House East Room.

At the start of the news conference, Biden relayed that he felt it was "particularly meaningful" to speak to Zelensky in person and "look each other in the eye." The Ukrainian president's leadership, Biden said, has inspired the world.

"We understand in our bones that Ukraine's fight is part of something much bigger," Biden continued.

Biden said Zelensky has shown his "strong stand against aggression in the face of the imperial appetites of autocrats," and said the US was standing alongside Ukraine in maintaining "core principles of sovereignty and territorial integrity."

Both Biden and Zelensky addressed the Russians during the news conference, with the Ukranian president repeatedly calling Russian forces "terrorists" and Biden underscoring the importance of being "clear" about Russia's actions.

"It is purposely attacking Ukraine critical infrastructure, destroying the system to provide heat and light (to) Ukrainian people during the coldest, darkest part of the year. Russia is using winter as a weapon, freezing people, starving people, cutting them off from one another," Biden said. The war, Biden later argued, "could end today if Putin had any dignity at all and did the right thing and just ... pulled out. But that's not gonna happen."

But the two leaders, it seems, still have different perspectives on their approach to pursuing peace with Russia.

Early in the news conference, Biden said Zelensky was open to pursuing a "just peace." Later, when asked by a reporter to share his idea of a fair way to end the war, the Ukrainian leader responded, "For me, as a president, just peace is no compromises as to the sovereignty, freedom and territorial integrity of my country, the payback for all the damages inflicted by Russian aggression."

"There can't be any just peace in the war that was imposed on us by these ... inhumans, I would say," he added.

Meeting comes at a critical moment

Zelensky arrived to the South Lawn just after 2 p.m. ET, eschewing a suit for his now-familiar military green shirt. A military honor guard lined the White House driveway as his black vehicle pulled toward the building.

"I understand that we have very important topics and we'll discuss them, everything, so many challenges in Ukraine, in Europe, in the world, from energy to the situation on the battlefield," Zelensky said in the Oval Office. "But first of all, really, all my appreciations from my heart, from the heart of Ukrainians, all Ukrainians, from our nation."

The wartime visit was meant to demonstrate in stirring fashion the continued American commitment to Ukraine at a moment when Biden's ability to maintain that support at home and abroad is being tested.

It has also been an opportunity for Biden and top American officials to sound out Zelensky on how he views the trajectory of the conflict, and to offer their thoughts on what it would take to bring the war to an end.

"Together with our partners, we're also going to impose costs on the Kremlin and will support Ukraine in pursuing a just peace," Biden said in the Oval Office, a reference to how Zelensky has said he hopes to see the war end. "President Zelensky, the United States stands with the brave people in Ukraine."

Sitting before a roaring fireplace, Zelensky offered Biden a military cross medal from a Ukrainian soldier serving on the front lines.

"He said, 'Give it to a very brave president,'" Zelensky said.

"Undeserved but much appreciated," Biden replied as he accepted the medal, asking if it would be possible to contact the Ukrainian soldier.

A surprise visit

The trip, which US and Ukrainian officials arranged in secret over the past week, came with heavy risks. After arriving in Poland by train, Zelensky flew to Washington aboard an American military aircraft, US officials said. He arrived in the US shortly after midday at Joint Base Andrews, just outside the nation's capital.

US President Joe Biden and Ukraine's President Volodymyr Zelensky meet in the Oval Office of the White House, in Washington, DC on December 21, 2022. - Zelensky is in Washington to meet with US President Joe Biden and address Congress -- his first trip abroad since Russia invaded in February. (Photo by Brendan SMIALOWSKI / AFP) (Photo by BRENDAN SMIALOWSKI/AFP via Getty Images)

Biden first discussed the prospect of Zelensky visiting Washington during a telephone call with the Ukrainian leader on December 11, an administration official said. A formal invitation was extended a week ago that Zelensky accepted, launching joint consultations on the security parameters of the risky, highly secretive trip.

Zelensky, who the official said was "very keen" to visit the US, determined those parameters met his needs, and the US set to work executing them. The trip was finally confirmed on Sunday.

Tight security was enforced around Zelensky's visit amid concerns that Russia wants to incapacitate the Ukrainian president, a source close to the Ukrainian leader told CNN on Wednesday. Because of this ongoing threat, senior top government officials -- as well as embassy staff in the US -- were not informed about the schedule of the visit.

According to the source, the military risk had to be calculated allowing the Ukrainian president to make the short overseas trip without jeopardizing the military situation. Scheduling also had to be worked with the White House to assess availability for this to happen.

In weighing a visit, Zelensky suggested he did not want to travel had there not been a significant development in the bilateral relationship between Ukraine and the US. Zelensky viewed the US decision to send Patriot missile defense systems to Ukraine as a major shift in the relationship between the two allies.

The new, $1.8 billion package Biden unveiled includes a Patriot surface-to-air missile system, which has been a longstanding request of Ukraine's to fend of Russian air attacks. CNN was first to report the US was expected to send the Patriot systems to Ukraine.

Unlike smaller air defense systems, Patriot missile batteries need much larger crews, requiring dozens of personnel to properly operate them. The training for Patriot missile batteries normally takes multiple months, a process the United States will now carry out under the pressure of near-daily aerial attacks from Russia.

The system is widely considered one of the most capable long-range weapons to defend airspace against incoming ballistic and cruise missiles, as well as some aircraft. Because of its long-range and high-altitude capability, it can potentially shoot down Russian missiles and aircraft far from their intended targets inside Ukraine.

During the news conference, Biden told CNN's Phil Mattingly that the missile system is defensive, not escalatory. Zelensky said the system is "something that will strengthen our air defense significantly."

"Every dollar of this investment for the United States is going to be a strengthening of global security and I know that the American leadership will be strong and will play important role in global scope," Zelensky added.

He also suggested Ukraine would want more of the systems.

CNN's Jake Tapper, MJ Lee, Matthew Chance and CNN's Rhea Mogul contributed to this report.