The two most senior officials in the US air force have been told to leave after a scathing report into the air force's handling of a mistaken shipment of nuclear weapons parts to Taiwan.
Robert Gates, US defence secretary, ordered the resignations of General Michael Mosley, air force chief of staff, and Michael Wynne, the air force secretary.
In announcing the resignations on Thursday, Gates cited two embarrassing incidents in the past year.
In one, a B-52 bomber was mistakenly armed with six nuclear-tipped cruise missiles and flown across the US without the crew realising nuclear weapons were on board.
In the other, four electrical fuses for ballistic missile warheads were mistakenly sent to Taiwan instead of helicopter batteries that had been ordered.
Internal investigation
Gates said an internal investigation found a common theme in the B-52 and Taiwan incidents: "a decline in the Air Force's nuclear mission focus and performance".
He said that his decision to remove Wynne and Moseley was based on the findings of an investigation of the Taiwan debacle by Admiral Kirkland Donald, which found a "lack of a critical self-assessment culture" in the air force, making it unlikely that weaknesses in the way critical materials such as nuclear weapons are handled could be corrected.
He also said that Donald found a "lack of effective air force leadership oversight" of its nuclear mission.
Moseley said "as the air force's senior uniformed leader, I take full responsibility for events which have hurt the air force's reputation or raised a question of every airman's commitment to our core values".
Wynne said he "read with regret" the findings of the report into the Taiwan debacle.
Gates said he would make recommendations to the US president shortly on a new air force chief of staff and civilian secretary.