Combat without declaration of war

The last declaration of war in the United States was in 1941.  Yet, we've been in plenty of major "conflicts" that our presidential leadership has directed.  It is disturbing to think that we don't have checks and balances for such important matters.  Marvin Kalb has written a book on this topic, The Road to War: Presidential Commitments Honored and Betrayed, and has an interview on PBS Newshour; Diminishing checks and balances for U.S. Commanders in Chief considering war.