Jim Urquhart, Associated Press
This Jan. 27, 2010, file photo, shows the main gate at Dugway Proving Ground military base, about 85 miles southwest Salt Lake City, Utah.

HAIPHONG, Vietnam — U.S. Defense Secretary Ash Carter says he'll find out who was responsible for the mistaken shipments of live anthrax to 11 states and two countries, and he'll "hold them accountable."

Carter calls the shipments an "unfortunate incident." He says the Pentagon will make sure that any health problems are avoided and work to ensure it never happens again.

Live anthrax samples from the Army's Dugway Proving Ground in Utah were mistakenly sent to 24 laboratories, including ones in Australia and South Korea. Questions have been raised about possible flaws in Dugway's procedures to ensure that anthrax samples were made fully inert before shipping them to labs.

Carter spoke Sunday after a visit to the Vietnamese Navy's headquarters at the port city of Haiphong.