Washington DC - President Donald Trump on Sunday confirmed the US would send Patriot air defense systems to Ukraine and hinted at new sanctions on Russia as his patience with Vladimir Putin wears thin.

Trump's announcement of the much-needed weapons for Ukraine came after he earlier said he would make a "major statement... on Russia" on Monday.

"We will send them Patriots, which they desperately need," Trump said Sunday, without specifying how many weapons he would send.

"I haven't agreed on the number yet, but they're going to have some because they do need protection," he told reporters at Joint Base Andrews, as he returned from watching the FIFA Club World Cup final in New Jersey.

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The White House has U-turned from initially announcing that it would pause some arms deliveries to Kyiv, instead striking a new deal which would involve NATO paying the US for some of the weapons it sends to Ukraine.

"We basically are going to send them various pieces of very sophisticated military, and they're going to pay us 100% for them," said Trump, who is also slated to meet NATO Secretary General Mark Rutte this week. "It'll be business for us."

Earlier this week, President Volodymyr Zelensky said Ukraine was "close to reaching a multi-level agreement on new Patriot systems and missiles for them."

Trump also repeated that he was "disappointed" in Putin, as he grows increasingly exasperated with the Russian leader.

"Putin really surprised a lot of people. He talks nice and then he bombs everybody in the evening," the Republican said Sunday.

He also hinted he might be ready to step up the pressure on Russia as momentum for a new sanctions package grows in Congress.

"We're going to see what we will see tomorrow, OK?" Trump said when asked about sanctions.