[img]http://d.yimg.com/a/p/rids/20091228/i/ra3328912559.jpg?x=130&y=126&q=85&sig=yrqa8saItuylQ4Fx1W3bHA--[/img]AP - President Barack Obama on Monday vowed to use "every element of our national power" to keep Americans safe and said the failed Christmas Day plot to blow up a Detroit-bound airliner was "a serious reminder" of the need to continually adapt security measures against changing terrorist threats.