"Martyrdom" in Mosul?

It now looks like the deadly attack in Mosul yesterday was the work of a suicide bomber:

"New evidence shows the bombing of a U.S. military mess tent in the northern Iraqi city of Mosul on Tuesday -- which killed 22 people and wounded 69 others -- was a suicide attack, ABC News has learned."

"Investigators at the base have found remnants of a torso and a suicide vest that was probably a backpack, sources told ABC News, indicating that the attack was a suicide bombing."

"The bombing at the mess tent at Forward Operating Base Marez in Mosul was one of the deadliest attacks against U.S. troops in Iraq since the start of the war. Early reports indicated that the massive explosion might have been the result of a rocket attack."

"But a radical Sunni Muslim group, the Ansar al-Sunnah Army, later claimed responsibility for the attack and said it was a 'martyrdom operation,' a reference to a suicide bomber."