If Michael Chertoff has one regret from his tenure as US secretary of Homeland Security (2005-2009), it's Iraq. He says the US-led war there not only distracted from Afghanistan, but the unclear mission and lack of post-war planning ultimately turned Iraq into "a magnet for all kinds of attacks on Americans, that absorbed more resources, more attention, and more patients." Watch his interview with Ian Bremmer on this episode of GZERO World.

Watch the episode: Is America Safer Since 9/11?