Article I, Section 8. Clause 11 of the U.S. Constitution reads [The Congress shall have Power ...] To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water; ...
In other words, only Congress, not the President, can declare war.
But the current President is conducting undeclared wars in Syria, Iraq and Yemen, and threating Iran. He is unofficially involved in the wars in Israel and Ukraine. He is also making commitments in NATO and with other nations that could thrust the U.S. into more wars, possibly nuclear wars.