America's Transatlantic allies are "weak" and failing to control migration, the US president has said

US President Donald Trump has denounced Western Europe as a "decaying" group of nations led by "weak" leaders, accusing its governments of mishandling migration and failing to help end the Ukraine conflict.

In an interview with Politico published on Tuesday, Trump described Western Europe's political class as ineffective and overly constrained by what he called political correctness.

"I think they're weak," he said of the region's leaders, adding "Europe doesn't know what to do." 

Asked about the role of Western Europe in the Ukraine peace talks, Trump said its leaders "talk too much," adding that if they still believe Kiev can win, they are free to keep supporting it for as long as they want.

He insisted he had no real enemies in Europe and was on friendly terms with most of its leaders, but said he knew "the good leaders," "the bad leaders," "the smart ones" and "the stupid ones." 

"You got some real stupid ones too," Trump said.

Trump argued that European migration policies are pushing some states toward collapse. "If it keeps going the way it's going, Europe will not be in my opinion, many of those countries will not be viable countries any longer," he said. "Their immigration policy is a disaster. What they're doing with immigration is a disaster."

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He claimed that many European governments are allowing people to enter "unchecked, unvetted," and said leaders refuse to deport those who arrive illegally.

"They want to be politically correct... and they don't want to send them back to where they came from," Trump said. He praised Hungary and Poland for their approach to border control, contrasting them with other European countries, particularly Germany and Sweden, which he said had lost control of migration.