Asahi wrote that the U.S. military resumed flights of Futenma-based CH-53E helicopters on Sept. 7 following the incident in Okinawa on Aug. 27 in which a window fell into the sea from one of the aircraft, noting that the U.S. military has still not disclosed the cause of the incident. The paper wrote that the Heritage Foundation pointed out in a report released in October 2018 that the CH-53Es are aging and only 37% of the 143 helicopters are regarded as flyable. According to the paper, the U.S. Marines responded to Asahi’s inquiry on the continued use of CH-53Es on Sept. 13 by saying that the aircraft is reliable in terms of training and operation.