US President Donald Trump on Tuesday issued a sharp rebuke of Russian President Vladimir Putin after saying Washington would send Ukraine more weapons to help defend itself amid Russia's continued invasion.

Moscow has ramped up attacks on Ukraine with almost daily drone and missile strikes across the country, all while the Trump administration had been pushing to bring an end to the war.

What exactly did Trump say?

Trump accused Putin of being disingenuous in his dealings with Washington, using an expletive that reflected his growing frustration.

"We get a lot of bulls**t thrown at us by Putin," Trump said at the White House on Tuesday. "He's very nice all the time, but it turns out to be meaningless."

"Putin is not treating human beings right. He's killing too many people," Trump continued, as he explained his decision.

On Monday, the US president said more weapons would be sent because the Ukrainians "have to be able to defend themselves."

"They're getting hit very hard now," he added. "We're going to have to send more weapons, defensive weapons, primarily," Trump said.

The US has been the largest contributor of military support for Ukraine and there had been concerns over the status of continued aid when Trump began his second term in office.

Trump has made a number of concessions to Moscow, and rolled back the vast amount of aid provided by his predecessor, Joe Biden.

Zelenskyy orders push for more US air defense supplies

On the back of Trump's announcement about more weapons, Ukrainian President Volodymyr Zelenskyy said he had ordered an expansion of contacts with the US to secure "critical deliveries" of military aid, especially air defense systems.

"Today, I instructed the minister of defence and the commander in chief to intensify all contacts with the American side," Zelenskyy said in his nightly address on Tuesday.

The Ukrainian president said Kyiv now had the political backing it needed and must act fast to protect its people and frontline positions. He called the deliveries vital for saving lives and defending cities and villages.

Why is Trump sending more weapons to Ukraine?

Trump appears to have grown increasingly frustrated with Russian President Vladimir Putin and last week said there had been "no progress" to bring an end to Moscow's continued invasion.

Following a call on Thursday with the Russian leader, Trump said he was "very disappointed with the conversation" and added "I don't think he's looking to stop [the war] and that's too bad."

It was the sixth publicly disclosed conversation between Trump and Putin since his return to the White House.

On Tuesday, the Kremlin said that sending arms to Ukraine prolonged the fighting.

"It is obvious of course that these actions probably do not align with attempts to promote a peaceful resolution," Kremlin spokesman Dmitry Peskov was quoted by Russian news agencies as saying in a briefing.

Peskov said that it would take time to determine the amounts and types of weapons the US would be supplying.

Ukraine replacing US ambassador — report

Meanwhile, Ukraine's President Volodymyr Zelenskyy has agreed to replace his country's ambassador to the US, according to the Financial Times.

The UK publication cited sources familiar with the matter as saying the leaders had been in talks over possible successors with it being speculated the move was an attempt by Zelenskyy to appease Trump.

Oksana Makarova has held the position as ambassador in Washington since 2021 and has faced Republican criticism for being too close to the Democratic Party.

Trump's Ukraine envoy, Keith Kellogg, will be attending an international aid conference for Ukraine in Rome in the coming days, the Reuters news agency has reported, citing an Italian government source.

Edited by: Elizabeth Schumacher