U.S. President Donald Trump defended Sunday his growing ties with Russia amid criticism over his stance on Ukraine, arguing that Washington should reduce its focus on Vladimir Putin.

"We should spend less time worrying about Putin and more time worrying about migrant rape gangs, drug lords, murderers and people from mental institutions entering our country – so that we don't end up like Europe!" Trump wrote on his Truth Social platform Sunday night.

Trump's shift in approach to the war and Russia was evident days earlier when he criticized Ukraine President Volodymyr Zelenskyy in front of reporters at the White House.

The rare public confrontation – with Trump calling Zelenskyy "disrespectful" – led to Zelenskyy leaving the White House without signing a pact on sharing mineral rights.

Trump's growing rapport with Putin has raised alarms in Europe and within the U.S. Democratic Party, who have voiced national security concerns.

"The White House has become an arm of the Kremlin," said Democratic Sen. Chris Murphy, one of Trump's most vocal critics. "It appears America is trying to align itself with dictators," he told CNN.

Meanwhile, Trump’s Republican Party has largely supported him, with top officials suggesting that Zelenskyy step down to facilitate a peace deal with Moscow.

"We need a leader who can deal with us, eventually deal with the Russians, and end this war," National Security Advisor Mike Waltz said on CNN Sunday.