Ukrainian President Volodymyr Zelenskyy urged for more U.S. support as he told Congress that aid to the country was an investment in democracy and "not charity."
In his address to U.S. lawmakers, Zelenskyy invoked American battles against the Nazis in World War II to press for more assistance for Ukraine's war effort against Russia.
His comments on Wednesday come as Republicans – some of whom have voiced increasing skepticism about sending so much aid to Ukraine – are set to take control of the U.S. House of Representatives from Democrats on Jan. 3.
Some hardline Republicans have even urged an end to aid and an audit to trace how allocated money has been spent.
"Your money is not charity. It is an investment in the global security and democracy that we handle in the most responsible way," Zelenskyy told a joint session of the U.S. Senate and House of Representatives, speaking in English.
The world is too interconnected to allow any country to stand aside and feel safe, Zelenskyy said as he appealed for bipartisan support.
Earlier, Zelenskyy, wearing his trademark olive green trousers and sweater on his first foreign wartime visit, met President Joe Biden, who called for support to keep flowing in 2023.
The United States also announced another $1.85 billion in military aid for Ukraine, including a Patriot air defense system to help it ward off barrages of Russian missiles.
Zelenskyy said the Patriot system was an important step in creating an air shield.
"This is the only way that we can deprive the terrorist state of its main instrument of terror – the possibility to hit our cities, our energy," Zelenskyy told a White House news conference, standing next to Biden.
"We would like to get more Patriots ... we are in war," Zelenskyy told reporters at the White House.
Russia says it launched its "special military operation" in Ukraine in February to rid it of nationalists and protect Russian-speaking communities. Ukraine and the West describe Russia's actions as an unprovoked war of aggression.
Ukraine has come under repeated Russian strikes targeting its energy infrastructure in recent weeks, leaving millions without power or running water in the dead of a freezing winter.
'Empty words'
TASS news agency cited Russia's U.S. ambassador as saying that Zelenskyy's visit confirmed that U.S. statements about not wanting a conflict with Russia were empty words.
America's provocative actions in Ukraine were leading to an escalation the consequences of which were impossible to imagine, TASS cited Anatoly Antonov as saying.
Russia said last week, Patriot systems, if delivered to Ukraine, would be a legitimate target for Russian strikes.
Zelenskyy joined a long list of world leaders to address joint meetings of the U.S. Senate and House, a tradition that began in 1874 with a visit by Hawaiian King Kalakaua and included almost legendary wartime visits by British Prime Minister Winston Churchill, kings, queens and one pope.
House members and senators from both parties leaped to their feet to cheer parts of Zelenskyy's speech as he likened his country's battle to World War II and even the American Revolution.
Referencing former U.S. President Franklin D. Roosevelt, who served between 1933 and 1945, and efforts to liberate Europe from Nazi occupation, Zelenskyy appealed to Americans as they gathered with family for Christmas.
"Just like the brave American soldiers, which held their lines and fought back Hitler's forces during the Christmas of 1944, brave Ukrainian soldiers are doing the same to Putin's forces this Christmas," he said.
Congress is on the verge of approving an additional $44.9 billion in emergency military and economic assistance, on top of some $50 billion already sent to Ukraine this year as Europe's biggest land conflict since World War II drags on.
White House National Security Council spokesman John Kirby said Washington was seeing no sign that Russian President Vladimir Putin was willing to engage in peacemaking.
Kremlin spokesman Dmitry Peskov said more Western arms supplies to Ukraine would lead to a "deepening" of the conflict.
Zelenskyy said a "just peace" with Russia meant no compromises on Ukraine's sovereignty and territorial integrity.
Bakhmut
Russian forces attacked targets in the Zaporizhzhia region and pushed to advance near the battered eastern front-line towns of Bakhmut and Avdiivka, the focal point of fighting in the Donetsk region, Ukraine's military said on Wednesday evening.
The commander of Ukraine's "Freedom" battalion, Petro Kuzyk, helping to defend Bakhmut, told the website of Espreso TV: "Each day, there are anywhere from seven to 10 attempts to storm our positions. And it's the same at night."
"They won't be able to take Bakhmut, but if they take the heights above it and set up their artillery and cut our logistical arteries, that will make the situation much more difficult," Kuzyk said.
Putin has promised to give his military whatever it needs to prosecute the war nearing the end of its 10th month and backed a plan to boost the size of the armed forces by more than 30%.