We who have grown up with what is deemed ethics and morals find it "cowardly" to plant a bomb on a plane taking innocent lives. We find it cowardly to strap an explosive vest to a child or a lady and send them off to blow up not only themselves but innocents. We find it cowardly to stand behind a person tied to a chair, unable to move in any direction, and cut off his head. We who do so have not been raised in a thousands of years old culture that looks on acts such as these not as cowardly, but as necessary and required by the God we worship.
There are those who would similarly say they find it cowardly to drop bombs from 20,000 feet that take out terrorist cells and cause collateral damage. Some will argue we who fight terrorism effect just as much carnage... or more... than the terrorists themselves.
My take is that this world will never see everyone living side by side in peace and contentment. We will always have some one, some group, some religion, some political agenda taking innocent lives in the name of greed, power, religion, etc. Today's life/death issue on God's Green Earth is a rising wave of Islamic fundamentalism that believes anyone who does not worship exactly as they is an infidel and is to be put to death. And, there is no way to politely talk these people out of a religion and belief instilled since birth. They recruit, they indoctrinate, they murder, they perform "cowardly" acts... and will until they either succeed in world-wide "success" or are all sent to "Allahville" in the sky.