PENTAGON - Islamic State fighters have begun forcing civilians in Mosul into buildings rigged to explode, according to top U.S. commanders, and the new tactic could explain why scores of people died in the Iraqi city recently.
Senior American officials said Wednesday they first noticed IS herding civilians into apparently booby-trapped buildings when fighting recently began for control of western Mosul — an area of the large northern Iraqi city where Islamic State still holds territory.
A senior official told Pentagon reporters battlefield video from western Mosul shows civilians fleeing from a building where an American airstrike hit a sniper on the roof but did not damage the structure.
Army Lieutenant General Stephen Townsend, the top American commander on the ground in Iraq and Syria, also told reporters that Iraqi counterterrorism forces have found and disarmed explosives set to blow up two buildings during the past week. The Iraqi squads saved the lives of 25 hostages in one instance, Townsend said, and 45 civilians in the other.
Information about the new Islamic State tactics came as the top general for U.S. military operations in the Middle East said a formal investigation has been launched into the circumstances that caused estimates of about 100 civilian deaths in Mosul on a single day earlier this month.
General Joseph Votel, the Army officer who heads the U.S. Central Command, described to lawmakers on Capitol Hill on Wednesday how the fight against Islamic State has changed in the dense urban terrain in western Mosul.
Islamic State fighters "understand our sensitivities to civilian casualties, and they are exploiting that," Votel told members of Congress at a meeting of the House Armed Services Committee.
The investigation of the Mosul incident on March 17, led by Air Force Brigadier General Matthew Isler, will look at all factors in the massive loss of life that day. U.S. officials have said they are reviewing images from more than 700 videos covering 10 days of airstrikes, along with information from human-rights groups and intelligence provided by Iraqi forces.
The general said that while U.S. military leaders "at the tactical edge" now have additional authorities needed in the fight, their level of care for preventing civilian casualties has not changed.
"We have not relaxed the rules of engagement," Votel said.
He accused Islamic State of deliberately using human shields and circulating false accusations about civilian casualties as a tool to hinder coalition operations.
'Fair chance we did it'
Townsend, also an Army general, told reporters in a conference call Tuesday from Baghdad that the U.S. military likely played a role in the civilian deaths.
"Because we struck in that area, I think there is a fair chance that we did it," Townsend said.
The American commander said Iraqi military leaders "firmly believe" that civilians were gathered by Islamic State in advance of the airstrike, either to lure the coalition into a trap that would kill civilians or possibly for use as human shields by the extremists.
Further questions of U.S. involvement have been raised based on the amount of damage in the area where civilian casualties were reported. According to Townsend, munitions used during the U.S. airstrike would not have collapsed an entire building. Since the building did collapse, he said that "actually contradicts" the conclusion that American firepower was responsible for extensive casualties.
U.S. personnel have inspected the site to conduct tests and gather information, the general added.
The United Nations has said at least 307 people were killed and 273 others wounded between February 17 and March 22 in western Mosul. It attributed the casualties to all sides involved in the fight for western Mosul: Iraqi and coalition airstrikes, Islamic State shellfire and improvised explosive devices detonated by the militants.
The Islamic State strategy "of using children, men and women to shield themselves from attack is cowardly and disgraceful," U.N. human rights chief Zeid Ra'ad Al Hussein said this week. "It breaches the most basic standards of human dignity and morality."