US confirms four American citizens killed by drones

The US justice secretary has acknowledged that four Americans have been killed abroad in drone strikes since 2009.

Eric Holder said only one individual had been specifically targeted - the radical cleric Anwar al Awlaki, who was killed in Yemen in 2011.

President Barack Obama is due to make a major speech on counter-terrorism on Thursday, laying out the thinking behind drone strikes, and the legal arguments.

Rajini Vaidyanathan reports.