WASHINGTON (AP) — Another embarrassing stumble by the U.S. nuclear missile force, this time a safety and security inspection failure, is raising questions about the Air Force's management of arguably the military's most sensitive mission.

The head of nuclear air forces, Lt. Gen. James M. Kowalski, revealed to The Associated Press on Tuesday that the 341st Missile Wing at Malmstrom Air Force Base, Mont., had failed what the military calls a "surety" inspection — a formal check on the unit's adherence to rules ensuring the safety, security and control of its nuclear weapons.

The 341st is one of three units that operate the Air Force's 450 Minuteman 3 intercontinental ballistic missiles, or ICBMs.

Kowalski, commander of Air Force Global Strike Command, said a team of "relatively low-ranking" airmen failed one exercise as part of a broader inspection, which began last week and ended Tuesday. He said that for security reasons he could not be specific about the team or the exercise, although he said the team did not include missile launch crew members.

"This unit fumbled on this exercise," Kowalski said by telephone from his headquarters at Barksdale Air Force Base, La., adding that this did not call into question the safety or control of nuclear weapons at Malmstrom.

"The team did not demonstrate the right procedures," he said, and as a result was rated a failure.

To elaborate "could reveal a potential vulnerability" in the force, Kowalski said.

In a written statement on its website, Kowalski's command said there had been "tactical-level errors" in the snap exercise, revealing "discrepancies."

Without more details it is difficult to reliably judge the extent and severity of the problem uncovered at Malmstrom.

On Capitol Hill, a spokesman for Rep. Howard "Buck" McKeon, R-Calif., chairman of the House Armed Services Committee, said McKeon believes that "two troubling inspections in a row at two different missile wings is unacceptable."

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"It is his sense that the Air Force must refocus on the nuclear mission," spokesman John Noonan said. "The Air Force should hold failed leadership at the group and wing level accountable, recommit itself from the top down to the nuclear deterrent mission, and ensure a daily focus on its centrality to our nation's security."

In response to word of the failed inspection, the press secretary for the Pentagon, George Little, said the bottom line for nuclear forces hasn't changed: "Our nuclear forces remain fully capable and ready."

"While the fact that the unit made errors during this exercise is disappointing, this type of exercise is designed to push people to their limits and learn how to improve," Little said.

Asked whether the Air Force intends to take disciplinary action against anyone for the inspection failure, Kowalski said the Air Force is "looking into it." Overall, the 341st wing "did well," he said, earning ratings of excellent or outstanding in the majority of the 13 areas in which it was graded by inspectors. Those areas include management, administration, safety, security, emergency exercises, worker reliability and other facets of a mission that relies on teams of officers and enlisted personnel.

The acting secretary of the Air Force, Eric Fanning, will meet with Kowalski at his Barksdale headquarters on Wednesday to discuss the Malmstrom situation and other aspects of the broader nuclear mission, according to Brig. Gen. Les Kodlick, the top Air Force spokesman. Kodlick said the visit had been scheduled for "some time" and not in response to the failed inspection.

ICBM wings undergo multiple types of inspections. The one at Malmstrom was a "surety" inspection, which the Pentagon defines as "nuclear weapon system safety, security and control." The point is to ensure that no nuclear weapon is accidentally, inadvertently or deliberately armed or launched without presidential authority.

Kowalski said his command's inspector general has conducted 14 such inspections since early 2010 with just two failures — both involving the 341st wing. The first was in February 2010. The second was this week.

The 341st also failed a safety and security inspection in 2008.

A different type of inspection of the 91st Missile Wing at Minot Air Force Base, N.D., in March of this year led the deputy commander of the wing's operations group to complain of "rot" in the force. Technically, the wing passed that inspection, but its missile crews earned the equivalent of a "D'' grade when tested on their mastery of Minuteman 3 launch operations using a simulator. The following month the 91st temporarily removed 17 officers from launch control duty — the first time such a large number had been pulled from duty.

In April the Pentagon reissued a public directive on responsibilities for ensuring nuclear weapons security. "Standards, plans, procedures, and other positive measures will be developed and maintained to ensure the (Pentagon) can accomplish its nuclear mission in a safe, secure, and reliable manner," the directive said.

In June, the commander in charge of training and proficiency of missile crews at Minot, Lt. Col. Randy Olson, was relieved of duty. The Air Force cited a "loss of confidence" in his leadership.

Launch operations were not part of the Malmstrom inspection failure, Kowalski said.

The trouble at Minot was the latest in a longer series of setbacks for the Air Force's nuclear mission, highlighted by a 2008 Pentagon advisory group report that found a "dramatic and unacceptable decline" in the Air Force's commitment to the mission, which has its origins in a Cold War standoff with the former Soviet Union.

Following a series of nuclear embarrassments in 2008 — including the inadvertent transport of six nuclear-tipped missiles on a B-52 bomber, whose pilot did not know they were aboard when he flew from Minot to Barksdale Air Force Base, La. — then-Defense Secretary Robert Gates fired the top two Air Force officials.

Kowalski's command was created in late 2009 as part of an effort to fix what was broken in the nuclear force. In Tuesday's interview, he said he is encouraged that inspections after 2009 began finding an increasing number of problems at the ICBM wings, followed by a decrease since 2011. He said this tells him that the Air Force has come up with more rigorous, effective means of inspecting, and that they are spurring change.

"This is a difficult inspection," he said, so occasional failures do not point to a systemic failure to adhere to safety and security regulations.

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