Under the constitution, only Congress can declare war. However, that power has been usurped innumerable times by the president. And the result is usually disastrous, as is the current case.
Toss in that the Executive should not use the military without authorisation from the people's representatives.
Article II, Section 2 which states:
"The president shall be
Commander in Chief of the Army and Navy of the United States, and of the
Militia of the several States, when called into the actual Service of
the United States"
Should be amended to:
"The Commander in Chief of the United States armed forces, and of the National Guards of the several States, when called into the actual Service of
the United States, shall be nominated by the senior military staff with the appointment ratified by congress. This position is responsible to and reports solely to the Legislature, unless there is a declared national emergency."
The routine administration of the military should be delegated to a Defence Council, a body officially charged with the direction and command of the Armed Forces.
While the administration of the military should be military, the ultimate control would rest with the legislature.
The power to declare war is vested in the legislature under the US Constitution: they should be the ones to have power over the military.