Zelenskyy said his country will persevere through the winter and celebrate Christmas. Alluding to Russian strikes on his country's infrastructure such as its energy resources, he said, "Even if there is no electricity, the light of our faith in ourselves will not be put out."

"If Russian missiles attack us, we'll do our best to protect ourselves. If they attack us with Iranian drones and our people will have to go to bomb shelters on Christmas Eve, Ukrainians will still sit down at the holiday table and cheer up each other, and we don't have to know everyone's wish as we know that all of us, millions of Ukrainians, wish the same: Victory," he said. "Only victory."

He thanked President Biden, "both parties" of Congress and the American people for supporting Ukraine over the last 10 months.

While continuing to ask for help with weapons and financial assistance, Zelenskyy reminded lawmakers that he has never asked for U.S. troops on the ground, which American leaders have long resisted.

"I believe in us and our alliance. Ukraine never asked the American soldiers to fight on our land instead of us. I assure you that Ukrainian soldiers can perfectly operate American tanks and planes themselves," he said to some laughs and applause.

"Your money is not charity. It's an investment in the global security and democracy that we handle in the most responsible way," he said, also to applause and cheers.

The speech comes as lawmakers consider billions in additional aid to Ukraine as part of a larger government spending package, which is seeing resistance from some House Republicans and calls on the right for more oversight on funding to the war-torn country.

Zelenskyy talked about his visit one day earlier to the front lines, in the city of Bakhmut in the Donbas region, which has seen months-long fighting, adding that the conflict there during Christmas resembles U.S. troops fighting Nazis at the Battle of the Bulge during World War II.

"Every inch of that land is soaked in blood, roaring guns sound every hour," he said. "The Russians' tactic is primitive. They burn down and destroy everything they see. They sent convicts to the front lines, to the war. They threw everything against, similar to the other tyranny, which is in the Battle of the Bulge."

"Just like the brave American soldiers who held their lines and fought back Hitler's forces during the Christmas of 1944, brave Ukrainian soldiers are doing this same to Putin's forces this Christmas," he said to a standing ovation. "Ukraine holds its lines and will never surrender."

"So here in the front line, the tyranny which has no lack of cruelty against the lives of free people, and your support is crucial -- not just to stand in such fight but to get to the turning point to win on the battlefield," he said.

Zelenskyy said Ukraine's fight is not just to protect their territory from Russia but to preserve their democratic way of life for younger generations.

"The struggle will define in what world our children and grandchildren will live, and then their children and grandchildren. It will define whether it will be a democracy of Ukrainians and for Americans, for all," he said. "This battle cannot be frozen or postponed. It cannot be ignored hoping that the ocean or something else will provide a protection."

"The world is too interconnected and interdependent to allow someone to stand aside," he said. "Our two nations are allies in this battle. And next year will be important, at the point when Ukrainian urge and American resolve must guarantee the future of our common freedom -- the freedom of people who stand for their values."

Lawmakers continued to encourage him with applause.