'US will do what's necessary to defend itself after attack in Iraq'

Speaking on ABC's "This Week" program, Austin said the United States was urging Iraq to quickly investigate the incident and determine who was responsible.

"We'll strike, if that's what we think we need to do, at a time and place of our own choosing. We demand the right to protect our troops," he said, adding that Iran would have to draw its own conclusions if and when the United States acts.