A remarkable shouting match broke out in the Oval Office on Friday between President Donald Trump and his Ukrainian counterpart Volodymyr Zelensky, an extraordinarily fractious display that only underscored the deeply uncertain future of American assistance to Kyiv.

Castigating Zelensky for not demonstrating enough gratitude for American support, Trump and his Vice President JD Vance raised their voices, accusing the besieged leader of standing in the way of a peace agreement.

“You’re not really in a good position right now.” Trump said. “You’re gambling with World War III.”

At one moment, Vance accused Zelensky of being “disrespectful” toward his American hosts.

“You’re not acting all that thankful,” Trump added.

“Have you said ‘thank you’ once?” Vance asked Zelensky.

It was an entirely unprecedented moment in recent US presidential history – a foreign wartime visitor coming under repeated scolding from his American hosts.

Ahead of his arrival, Trump had already voiced open hostility toward Zelensky, whom he termed a dictator.

But the tense 10-minute exchange in the Oval Office went well beyond any of the usual diplomatic rifts, allowing the gulf between the men to play out publicly in front of television cameras. It was about as angry as Trump has ever allowed himself to be seen in public.

“You’re either going to make a deal or we’re out,” the US president said, adding later: “If we’re out, you’ll fight it out. I don’t think it will be pretty.”

Vance, who has often sat silently in Oval Office meetings during the opening weeks of his vice presidency, sparked the tension with the visiting Ukrainian leader. Before joining Trump on the ticket last year, the freshman Ohio senator was among the loudest GOP critics of assistance to Ukraine – skepticism that he has carried into the White House.

The fiery exchanges on Friday served as a stark example of the dramatic whiplash in American foreign policy since Trump and Vance assumed office last month. The tensions escalated dramatically during a session that began with a series of pleasantries as Trump waxed aloud about his legacy.

“I hope I’m going to be remembered as a peacemaker,” Trump said as he looked ahead to the prospect of finalising a broader peace deal with Russia and Ukraine.

But the acrimony that exploded into full view raised questions about the prospects of reaching a peaceful solution, raising fresh alarm across Europe, where leaders have worked for weeks to warn Trump of Russian President Vladimir Putin’s past actions and potential future intentions with Ukraine.

Again and again, Trump has sided with Putin. But with voices raised in the Oval Office, Trump unleashed years of pent-up frustration toward Russia and Ukraine, which led to his first impeachment.

“Let me tell you, Putin went through a hell of a lot with me,” Trump said. “He went through a phony witch hunt where they used him and Russia, Russia, Russia.”

After the heated meeting, Trump said in a Truth Social post that Zelensky could come back to the White House “when he is ready for peace.”

“We had a very meaningful meeting in the White House today. Much was learned that could never be understood without conversation under such fire and pressure,” he said.

“It’s amazing what comes out through emotion, and I have determined that President Zelenskyy is not ready for Peace if America is involved, because he feels our involvement gives him a big advantage in negotiations. I don’t want advantage, I want PEACE. He disrespected the United States of America in its cherished Oval Office. He can come back when he is ready for Peace.”