US President Barack Obama has defended his administration\'s use of drones as legal, effective, and just. \"We are at war with an organization that right now would kill as many Americans as they could if we did not stop them first. So this is a just war,\" Obama said in a major policy speech at Washington\'s National Defense University on Thursday. \"Our nation is still threatened by terrorists,\" he pointed out, noting that \"We must recognize however, that the threat has shifted and evolved from the one that came to our shores on 9/11,\" he said. The US president claimed the strikes have been effective in targeting militants and have made the United States a safer country. Obama outlined the legal guidelines surrounding the use of unmanned aerial vehicles to wage war in distant lands. \"I don\'t not believe it would be constitutional for the government to target and kill any U.S. citizen...Nor should any president deploy armed drones over US soil. But when a US citizen goes abroad to wage war against American and is actively plotting to kill US citizens...his citizenship should no more serve as a shield than a sniper shooting down an innocent crowd should be protected from a swat team,\" he said. On Wednesday, US Attorney General Eric Holder admitted for the first time that four US citizens were murdered in assassination drone attacks conducted by the CIA in Pakistan and Yemen since 2011. Show Less >>