White House press secretary Jen Psaki has not ruled out the possibility of US military experts training Ukrainian fighters in European countries bordering Ukraine.

During a press briefing on Monday, the White House spokesperson also stated that American trainers who had previously been "on the ground for a period of time" have been "pulled back" for the time being.

Responding to a question, Psaki said that "we obviously had trainers on the ground for a period of time. We hadn’t — then we pulled them back. We obviously have a significant military presence in a range of countries in the region, but I can see if there’s anything that we are looking ahead to".

When it was pointed out to her that crossing trained Ukrainian fighters from neighboring countries — Poland, Slovakia, Hungary, or Romania (all NATO members) — could be interpreted as an "escalatory" measure by Russia, Psaki escaped a direct response.

"I mean, I think, really, our focus right now is on providing them and continuing to expedite the military assistance to them,” she replied.

“And the good news is that we still — through our coordination with them and our NATO Allies, we’re able to get them that assistance on the ground. They’re actively fighting now, so that’s where our focus really is at this point in time,” the press secretary stressed.

While US President Joe Biden has previously stated that no US troops will be deployed in Ukraine, successive US administrations have been secretly and openly assisting Kiev authorities since 2015.

Media reports have recently revealed that experts from the Central Intelligence Agency (CIA) have trained their Ukrainian counterparts at a secret facility in the southern United States, not to mention providing intelligence support and billions of dollars in arms to Ukrainian forces.

The CIA is also said to have experts stationed in eastern Ukraine to advise the country's paramilitary forces.

Aside from bilateral security, intelligence, and logistical assistance, the US was also providing assistance to Ukraine through NATO's "Comprehensive Assistance Package (CAP)," which was launched in 2016.

The CAP aims to strengthen "Ukraine's ability to provide for its own security and to implement broad security and defense reforms based on Euro-Atlantic principles," NATO claims.

While NATO has been wary of agreeing to Ukraine's repeated requests to impose a no-fly zone over Kiev in the aftermath of the Russian special military operation's launch on February 24, the Cold War-era military alliance says it is providing "practical and political" assistance to the eastern European country.

“The Alliance is helping to coordinate Ukraine’s requests for assistance and is supporting Allies in the delivery of humanitarian and non-lethal aid,” NATO claims on its website.

However, the 30-member military bloc has admitted that it has been coordinating the response of its member states, which have sent billions of dollars in lethal military equipment, ammunition, and other supplies to Ukraine to assist it in responding to the Russian military operation.

On its account, Pentagon spokesperson John Kirby stated, on Monday, that the United States military and other assistance to Ukraine was not provided under the "umbrella of NATO."

“These are sovereign decisions that individual nations are making about ways to assist Ukraine,” he stated.