The President has the power to defend the country without seeking Congressional approval. Yet, the power to order an attack against any country not posing an imminent or direct threat against the US rests with Congress.  The distinction being that Congress isn't granted the power of war by Article I, section 8, clause 11, but instead has limited power to declare war. The Founders also clearly meant this as an exception to the Presidents own executive power. 
Lobbing missiles into a sovereign nation, of which President Obama admitted to not posing a threat, is clearly an act of war and unconstitutional. Obviously, a presidential war becomes a political or policy question, rather than a legal one. Otherwise, the President's own words could be used to begin impeachment hearings for violating the War Powers Act. Admittedly, war does not fall under foreign policy in the US Constitution, but instead law.
That Americans finally have begun to question the last 50 years of US military engagements or presidential wars, especially those not authorized by Congress: Korean War, Gulf War, Bosnian War, War in Afghanistan, Haiti etc., is a heartening movement that needs to continue growing in order to protect our own sovereignty.
"Now let me be clear  I suffer no illusions about Moammar Gadhafi. He is a brutal man. A ruthless man. A man who butchers his own people to secure his own power. He has repeatedly defied international demands, thwarted international sanctions, developed chemical and biological weapons, and coveted nuclear capacity.
 
Hes a bad guy. The world, and the Libyan people, would be better off without him.
 
But I also know that Gadhafi poses no imminent and direct threat to the United States, or to his neighbors, that the Libyan economy is in shambles, that the Libyan military a fraction of its former strength, and that in concert with the international community he can be contained until, in the way of all petty dictators, he falls away into the dustbin of history.
 
I know that even a successful military effort against Libya will require US involvement of undetermined length, at undetermined cost, with undetermined consequences. I know that bombing Libya without a clear rationale and without strong international support will only fan the flames of the Middle East, and encourage the worst, rather than best, impulses of the Arab world, and strengthen the recruitment arm of al-Qaeda.
 
I am not opposed to all wars. Im opposed to dumb wars."
Section 1541(c) of the War Powers Act:
The constitutional powers of the President as Commander-in-Chief to introduce United States Armed Forces into hostilities, or into situations where imminent involvement in hostilities is clearly indicated by the circumstances, are exercised only pursuant to
 
1. a declaration of war,
2. specific statutory authorization, or
3. a national emergency created by attack upon the United States, its territories or possessions, or its armed forces.