According to a former White House Russia advisor, President Donald Trump's foreign policy has made Russia feel like it can invade Ukraine.

In an interview with CNN Hill, an expert on Russia who advised Trump talked about the differences between his approach to foreign policy and that of President Joe Biden.

She said that the foreign policy of Trump was driven by personal interests and impulses.

Hill said there was no Team America for Trump. Not once. Not for a second.

Hill recalled that Trump had disdain for NATO and praised Russia's authoritarian leader, Vladimir Putin. She mentioned that he was campaigning to get dirt on Biden in the run up to the 2020 election. The first impeachment of Trump was caused by the Ukraine pressure campaign.

All this did was say to Russia that Ukraine was a playground, and that's what they're doing now, according to Hill.

Hill shot to prominence when she testified during Trump's impeachment hearings, rebutting conspiracy theories promoted by Trump allies that sought to excuse Russia of blame for interfering in the 2016 election.

She has gone on to speak critically of Trump's approach to foreign policy, and has said there were close parallels between how Trump sought to cling on to power after his defeat in 2020 and Putin's style of rule.

In an interview with CNN, Hill said that Biden had pulled NATO allies together for a display of resolve in face of Russian aggression, but warned that the crisis would likely drag on for some time as Russia tries to exert pressure on Ukraine.

The real challenge is keeping everyone together for a long time.