According to James Madison, in the Federal Convention of 1787, the phrase “make war” was changed to “declare war” in order to leave to the Executive Branch the power to repel sudden attacks but not to commence war without the explicit approval of the Legislative Branch. See The Debates in the Federal Convention of 1787 reported by James Madison: August 17, available at The Avalon Project (Yale Law School), https://avalon.law.yale.edu/18th_century/debates_817.asp.
The last time Congress declared war was in 1942, against certain Axis powers. Since then, every President has engaged in offensive hostilities without a declaration.
Query whether such actions (including the one in the linked webpage — Trump’s attack in Yemen, apparently against a civilian building) are legal under United States constitutional law, let alone international law.