US President Donald Trump on Monday warned Russia that he will impose "very severe" tariffs against Moscow's remaining trade partners if it doesn't end its war in Ukraine within 50 days.

"We're going to be doing secondary tariffs. If we don't have a deal in 50 days, it's very simple. And they'll be at 100 percent, and that's the way it is," Trump told reporters at the White House.

He said he is "we're very, very unhappy" with Russia as he met with NATO chief Mark Rutte in the White House.

Trump and Rutte also unveiled a deal under which the NATO military alliance would buy arms from the United States, including Patriot anti-missile batteries, and then distribute them to Ukraine to help it battle Russia's invasion.

"This is billions of dollars worth of military equipment is going to be purchased from the United States, going to NATO... and that's going to be quickly distributed to the battlefield," Trump said.

Rutte, a former Dutch prime minister, said Ukraine would get "massive numbers" of weapons under the deal.

Earlier too, Trump warned Putin to arrive at a negotiation with Kyiv shortly after starting his second term in January, as he sought to honor his election campaign promise to end the Ukraine war within 24 hours.