In respect to the war in Bosnia, which was never officially declared either, there was at least a sliver of congressional approval. According to a report written by Richard F. Grimmett from the Foreign Affairs and National Defense Division of the Federation of American Scientists on November 25th 1996:
"On August 13, 1992, the U.N. Security Council adopted Resolution 770 calling on all nations to take "all measures necessary" to facilitate the delivery of humanitarian assistance to Sarajevo. On August 11, 1992, the Senate had passed S.Res. 330 urging the President to work for such a resolution and pledging funds for participation, but saying that no U.S. military personnel should be introduced into hostilities without clearly defined objectives. On the same day, the House passed H.Res. 554 urging the Security Council to authorize measures, including the use of force, to ensure humanitarian relief. Thus, both chambers of Congress supported action but not by binding legislation authorizing the use of U.S. forces."
Though troops were eventually sent to Bosnia, these resolutions provide a record of at least some attempt at congressional oversight.
On Page 3 of the report the White House states:
"Moreover, the Libyan government's actions posed a significant threat to regional peace and security."
It goes on to cite refugees fleeing to other countries as the cause for regional instability, but again this does not explain how this presented an imminent threat to the United States. Indeed Hitler invading his neighbors presented an even greater regional instability that would of course affect the future security of the United States, but that didn't stop the United States from getting an official declaration of war from Congress before bombing Germany (and only after we were attacked by Japan, I might add). Again, there is no reason a vote on bombing Libya couldn't have been taken before the United States got involved.
For the rest of pages 3 and 4 the White House argues that had the United States not taken action in Libya the U.N.'s credibility would have been in question and that essentially the U.N. resolutions cited before would have been shown to have no teeth.
As demonstrated earlier by the U.N.'s own charter, the resolutions don't have any teeth...not without validation from each member nations' respective constitutional processes.
Page 5: "Political and Military Objectives and Means"
"The President has honored his commitment to focus the preponderance of our military effort on the front end of operations in Libya, using our unique assets to destroy key regime military targets and air defense capabilities in order to establish a no-fly zone (again, these are acts of war) and enable protection of civilians as part of the enforcement of UNSCR 1973. These actions set the conditions so that, after a limited time, command of these operations transferred to NATO. Since that April 4 transition, U.S. military involvement has been limited to a supporting role, enabling our allies and partners to ensure the safety of Libyan civilians."
The notion that the NATO mission in Libya is enabling the protection of civilians is a joke. Libyan rebels are carrying out genocide and NATO bombs are killing civilians, and damaging civilian buildings, such as Al Fateh University, Campus B. There's even evidence that depleted uranium bombs are being used by NATO forces.
In regards to the military involvement only being in a supportive role after April 4th, according to an Associated Press article posted on the Army Times' website on April 13th 2011:
"Pentagon officials disclosed Wednesday that American fighter jets have continued airstrikes inside the country even after the United States turned the mission over to NATO last week."
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