The Obama administration publicly justified its use of unmanned drones to target suspected terrorists overseas for the first time on Monday, with a top official saying the strikes are conducted "in full accordance with the law."

WASHINGTON (CNN) -- The Obama administration publicly justified its use of unmanned drones to target suspected terrorists overseas for the first time on Monday, with a top official saying the strikes are conducted "in full accordance with the law."

John Brennan, President Barack Obama's top counterrorism adviser said strikes are used when the option of capture is not feasible. Brennan discussed the strikes during a Monday address at the Woodrow Wilson Center, a Washington think-tank.

"President Obama said here five years ago, if another nation cannot or will not take action, we will," Brennan said. "And it is an unfortunate fact that to save many innocent lives we are sometimes obliged to take lives -- the lives of terrorists who seek to murder our fellow citizens."

The program utilizes unmanned aerial vehicles, often equipped with Hellfire missiles, to target al Qaeda operatives in remote locations overseas -- often on the territory of U.S. allies such as Pakistan and Yemen. Brennan said the United States "respects national sovereignty and international law" and is guided by the laws of war in ordering those attacks.