The Ukrainian president, Volodymyr Zelenskiy, has given a defiant address to a joint session of the US Congress in which he vowed that his country would never abandon its resistance to Russian aggression – but said that Washington’s continued support is key to ultimate victory.

Zelenskiy was received with a standing ovation as he arrived to speak wearing his now trademark green military-style trousers and shirt. The Ukrainian leader was repeatedly met with long bursts of applause as he invoked US battles against Nazi Germany and President Franklin Roosevelt’s wartime commitments in a bid to keep American weapons supplies flowing for the war against Russia.

“Our two nations are allies in this battle and next year will be a turning point. I know it. The point when Ukrainian courage and American resolve must guarantee the future of our common freedom. The freedom of people who stand for their values,” he said.

The Ukrainian president left his country for the first time since Russia invaded 300 days ago, crossing into Poland earlier in the day and then flying to Washington, to make a direct appeal to Congress for continued military aid amid concern that the incoming Republican leadership of the House of Representatives might oppose proposals for an additional $45bn in weapons and other assistance next year.

The US has already supplied $22bn in military assistance to Ukraine since the Russians invaded in February. On Wednesday, the White House announced a further $1.85bn in aid including, for the first time, Patriot air defence missiles to protect Ukraine’s infrastructure, already crippled by Russian attacks.

Zelenskiy sought to win sceptics over with a speech that tied the future of the war, and freedom, to America’s commitment to Ukraine.

He said his country had defied expectations that it would not be able to hold out for more than a few weeks against Russia.

“Against all odds and doom and gloom, Ukraine didn’t fall. Ukraine is alive and kicking,” he said.

That survival had produced different kinds of victories, he said.

“We defeated Russia, in the battle for minds of the world. We have no fear. Nor should anyone in the world have it. Ukraine’s gained this victory and it gives us courage, which inspires the entire world.”

But, Zelenskiy said, the struggle on the battlefield remained, and America was central to what happened there.

“I know that everything depends on us, on the Ukrainian armed forces. Yet so much depends on the world. So much in the world depends on you,” he told Congress.

“Russia could stop its aggression, really, if it wanted to. But you can speed up our victory.”

Zelenskiy said that the day before flying to Washington he visited the frontline city of Bakhmut in the Donbas. He described the region as “soaked in blood”.

“Russians use everything they have against Bakhmut and other our beautiful cities. The occupiers have a significant advantage in artillery, they have an advantage in ammunition, they have much more missiles and planes than we ever had,” he said. “It’s true, but our defence forces stand.”

He compared Ukrainian soldiers to American troops who resisted Germans at the Battle of the Bulge in Christmas 1944.

And then he got to his point: Ukranians are fighting and dying. The least America can do is provide them with the weapons to resist.

“We have artillery. Yes. Thank you. Is it enough? Not really,” he said to laughter in the chamber.

Zelenskiy also sought to define his enemy in terms American politicians understand – as a terrorist state allied with another of the US’s enemies, Iran, which has supplied drones used in attacks on Ukrainian cities.

“Russia found an ally in this genocidal policy, Iran. The deadly drones sent to Russia in hundreds and 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. We must do it.”

Zelenskiy also played to the American reverence for the flag. He unfurled a blue and yellow Ukrainian standard he said had come from the front line. The speaker of the House, Nancy Pelosi, and Vice-president Kamala Harris held it up.

“This flag is a symbol of our victory in this war. We stand, we fight and we will win because we are united – Ukraine, America and the entire free world,” he said.

It was not clear if Zelenskiy’s performance was enough to win over sceptical Republicans in Congress but he got the reassurance he wanted at a White House meeting earlier in the day.

“You will never stand alone,” President Biden told the Ukrainian leader.