The president, as commander in chief, can send troops anywhere at any time, but a formal declaration of war must be declared by at least 2/3 of the states. the supreme court. congress. the executive branch.
Congress must issue a declaration of war, but since Vietnam, the US has gotten around that by claiming that they are taking 'defensive' actions or that it is a 'security' mission. It's a clever way to get around it.
