The president does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation. As commander in chief, the president does have a duty to protect and defend the United States. In instances of self-defense, the president would be within his constitutional authority to act before advising Congress or seeking its consent.
The essential factor of military success is speed, that is taking advantage of others' unpreparedness or lack of foresight, their failure to catch up, going by routes they do not expect, attacking where they are not on guard. This you cannot accomplish with hesitation.