LOWERING THE BARRIERS TO WAR

Over the past decade, the US military has shifted the way it fights its wars, deploying more unmanned systems in the battlefield than ever before. Today there are more than 7,000 drones and 12,000 ground robots in use by all branches of the military.

These systems mean less American deaths. They also mean less political risk for the US when it takes acts of lethal force -- often outside of official war zones.

But US lethal drone strikes in countries like Pakistan have brought up serious questions about the legal and political implications of using these systems.

Fault Lines looks at how these new weapons of choice are allowing the US to stretch the international laws of war and what it could mean when more and more autonomy is developed for these lethal machines.