It is in this context that the United States has taken lethal, targeted action against al Qaeda and its associated forces, including with remotely piloted aircraft commonly referred to as drones. As was true in previous armed conflicts, this new technology raises profound questions - about who is targeted, and why; about civilian casualties, and the risk of creating new enemies; about the legality of such strikes under U.S. and international law; about accountability and morality.

Let me address these questions. To begin with, our actions are effective. Don't take my word for it. In the intelligence gathered at bin Laden's compound, we found that he wrote, "we could lose the reserves to the enemy's air strikes. We cannot fight air strikes with explosives." Other communications from al Qaeda operatives confirm this as well. Dozens of highly skilled al Qaeda commanders, trainers, bomb makers, and operatives have been taken off the battlefield. Plots have been disrupted that would have targeted international aviation, U.S. transit systems, European cities and our troops in Afghanistan. Simply put, these strikes have saved lives.

Moreover, America's actions are legal. We were attacked on 9/11. Within a week, Congress overwhelmingly authorized the use of force. Under domestic law, and international law, the United States is at war with al Qaeda, the Taliban, and their associated forces. 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 - a war waged proportionally, in last resort, and in self-defense.

And yet as our fight enters a new phase, America's legitimate claim of self-defense cannot be the end of the discussion. To say a military tactic is legal, or even effective, is not to say it is wise or moral in every instance. For the same human progress that gives us the technology to strike half a world away also demands the discipline to constrain that power - or risk abusing it. That's why, over the last four years, my Administration has worked vigorously to establish a framework that governs our use of force against terrorists - insisting upon clear guidelines, oversight and accountability that is now codified in Presidential Policy Guidance that I signed yesterday.

In the Afghan war theater, we must support our troops until the transition is complete at the end of 2014. That means we will continue to take strikes against high value al Qaeda targets, but also against forces that are massing to support attacks on coalition forces. However, by the end of 2014, we will no longer have the same need for force protection, and the progress we have made against core al Qaeda will reduce the need for unmanned strikes.

Beyond the Afghan theater, we only target al Qaeda and its associated forces. Even then, the use of drones is heavily constrained. America does not take strikes when we have the ability to capture individual terrorists - our preference is always to detain, interrogate, and prosecute them. America cannot take strikes wherever we choose - our actions are bound by consultations with partners, and respect for state sovereignty. America does not take strikes to punish individuals - we act against terrorists who pose a continuing and imminent threat to the American people, and when there are no other governments capable of effectively addressing the threat. And before any strike is taken, there must be near-certainty that no civilians will be killed or injured - the highest standard we can set.