A senior Pentagon official apologized Friday to Washington-area Muslims for the burning of Qurans at a military base in Afghanistan.

Peter Lavoy, acting assistant secretary of defense for Asia and Pacific security affairs, said the military is investigating what occurred and that all 140,000 coalition troops in Afghanistan are being retrained in the handling of religious materials.

Lavoy apologized multiple times during a brief speech during prayer services at the ADAMS Center in Sterling, one of the largest mosques in the country.

“I come here today to apologize on behalf of the Department of Defense for the incident that took place in Afghanistan this week,” Lavoy told worshippers, saying the burnings were done “unknowingly and improperly.”

Previously, the president of the United States issued his “deep regret” to the Afghan president for the apparent accident. “I wish to express my deep regret for the reported incident,” President Obama said in a letter to President Karzai. “I extend to you and the Afghan people my sincere apologies.” The Pentagon’s apology at a Virginia mosque occurred today.