Donald Trump is set to host Nato's Secretary General Mark Rutte in Washington this week, after the US President resumed weapons shipments to Ukraine.
On Sunday, Nato said Mr Rutte would meet Mr Trump, Secretary of State Marco Rubio, and Secretary of Defence Pete Hegseth, and members of Congress.
The White House said that the two leaders would hold a closed meeting in the Oval Office on Monday morning.
"I haven't agreed with nobody yet, but [Ukraine] are going to have stuff because they do need protection," Mr Trump told journalists on Sunday evening.
"But the European Union will pay, we're not paying anything for it," he said adding that the US would be sending patriot missile defence systems.
Mr Rutte's trip comes after Mr Trump last week said he would make a “major statement” about Russia on Monday.
It also comes after weeks of Mr Trump showing increasing frustration with Russian President Vladimir Putin's continued strikes on Russia.
Last week he said he was “strongly looking” at imposing new sanctions on Moscow.
Republican Senator Lindsey Graham on Sunday said the US would begin selling weapons to European allies that they can then provide to Ukraine.
“Putin has calculated that we would get tired and Europe would get weary – he made a huge mistake,” Mr Graham said in an interview on CBS.
“Nato is bigger and stronger, and we're more committed than ever to make sure he does not take Ukraine by force.”
William Taylor, a former US ambassador to Ukraine, said Mr Trump will probably reinforce his commitment to Nato during his meeting with Mr Rutte.
“When Putin hears that the Americans and the rest of Nato are solid, he has to re-evaluate,” Mr Taylor told Fox News on Sunday. “So this is part of that activity.”
The development comes after the Trump administration earlier this month had announced that it would pause some weapons shipments to Ukraine, including critical air defence interceptors and precision munitions due to concerns over declines in US stockpiles. Mr Trump later changed course and said transfers would continue via Nato countries.
Critics said slowing weapons transfers plays into Mr Putin's hands and could prolong the war, leaving Ukraine more vulnerable to Russian missile and drone attacks. Officials have also challenged whether US stockpiles were running low.
Mr Trump took office in January on a promise to swiftly end the war in Ukraine. He said weapons assistance to Ukraine was a waste of US taxpayers' money.
Under his “America First” approach to foreign policy, he sought to end US military support for Kyiv and reversed decades of foreign policy by initially seeking rapprochement with Mr Putin.
But in recent weeks, Mr Trump seemingly changed his tune on Russia, and its leader.
“Putin really surprised a lot of people," Mr Trump said on Sunday. "He talks nice and then he bombs everybody in the evening, but there's a little bit of a problem there. I don't like it.”
Meanwhile, Mr Graham, a Trump ally, is co-sponsoring a bill in the Senate for additional sanctions on Russia, which includes a 500 per cent tariff increase on goods imported from countries who continue to buy Russian oil.
Mr Graham said Mr Trump had approved pushing the legislation.
“I don't want to get ahead of the President, but stay tuned about seized assets,” Mr Graham said on Sunday.
