President Donald Trump said Tuesday that NATO countries should shoot down Russian aircraft that violate their airspace, a remark made during a meeting with Ukrainian President Volodymyr Zelenskyy at the U.N. General Assembly in New York.

Earlier in the day, Trump criticized the United Nations for failing to support his peace efforts and accused it of “creating new problems” for the U.S. and its allies.

He singled out migration as the UN’s “biggest failure,” accusing the body of aiding illegal immigration by providing assistance to migrants.

Trump argued that uncontrolled migration is destabilizing both Europe and the U.S., touting his administration’s policies of detentions and deportations as proof of success, Fox News has reported.

He also praised El Salvador for cooperating in detaining criminals sent back from the U.S.