The use of military force against a sovereign nation is an act of war. Article I, Section 8 of the Constitution explicitly grants Congress the sole power to declare war.

Missile strikes - or any other such action - against a sovereign nation is an act of war.

Unfortunately, since its passage in 1973, the War Powers Resolution has been stripped of its original purpose and has instead served as a temporary, de facto authorization for the executive branch to use military force whenever it deems it necessary.

Every decision to use military force is an excruciatingly difficult one.

If the use of military force, or the threat of use of military force, is necessary to bring about a political solution, NATO is prepared to do it,

On a number of occasions, military operations which involved
excessive use of force and other violations, haven't
necessarily been addressed,