The day before the terror attacks on September 11, 2001, former President Bill Clinton told a group of businessmen in Australia that he "could have killed" the man behind those attacks, Osama bin Laden, in 1998, but he decided against launching a strike out of concern for civilian casualties.
http://www.cbsnews.com/news/bill-clinton-i-could-have-killed-osama-bin-laden/
Great find!