THE STORY SO FAR

2013: The Air Force punished officers twice last year in separate incidents of blast doors being opened at a launch control center while one of two launch officers slept.

April 2013: 17 missile crew members in the 91st Missile Wing at Minot, N.D., are deemed temporarily unfit for duty and given weeks of remedial training.

Oct. 2013: The Air Force fires Maj. Gen. Michael Carey, commander of the 20th Air Force, which is responsible for the entire Minuteman 3 missile force, amid an investigation of an alcohol-related complaint.

Nov. 2013: Key members of the Air Force's nuclear missile force report feeling "burnout" from what they see as exhausting, unrewarding and stressful work.

Jan. 16: At least 34 nuclear missile launch officers are implicated in a cheating scandal and stripped of their certification. Also, three launch officers are among 11 officers at six bases implicated in an illegal-narcotics investigation.

With public trust and safety at stake, Defense Secretary Chuck Hagel ordered immediate actions Thursday to define the depth of trouble inside the nation’s nuclear force, which has been rocked by disclosures about security lapses, poor discipline, weak morale and other problems that raise questions about nuclear security.

It amounted to the most significant expression of high-level Pentagon concern about the nuclear force since 2008, when then-Defense Secretary Robert Gates fired the top uniformed and civilian officials in the Air Force following a series of mistakes that included an unauthorized flight of nuclear-armed cruise missiles across the country.

Hagel had recently said he was considering what may lay behind problems in the nuclear Air Force — many revealed by the media — but his chief spokesman said Thursday that the defense secretary concluded urgent remedies were needed.

“To the degree there are systemic problems in the training and professional standards of the nuclear career field, the secretary wants them solved,” the spokesman, Navy Rear Adm. John Kirby said. “To the degree there are gaps in our understanding or implementation of those standards, he wants them closed. And to the degree leaders have failed in their duties, he wants them held to account.”

Hagel summoned top military officials to a Pentagon conference, to be held within two weeks, to “raise and address” any personnel problems infesting the nuclear force, and he ordered an “action plan” be written within 60 days to explore nuclear force personnel issues, identify remedies, and put those fixes into place quickly. Hagel said he and the chairman of the Joint Chiefs of Staff, Army Gen. Martin Dempsey, will host the nuclear summit.

The Pentagon chief also said he would assemble a small group of outsiders with expertise in the nuclear field to conduct a broader review of the U.S. nuclear force, with a focus on personnel issues, and to recommend changes “that would help ensure the continued safety, security and effectiveness of our nuclear forces.”

Personnel failures within this force threaten to jeopardize the trust the American people have placed in us to keep our nuclear weapons safe and secure,” Hagel wrote in a memo to top military officials, including heads of the Air Force and Navy.

Sen. Mark Udall, D-Colo., chairman of the Senate subcommittee that oversees the nation’s strategic nuclear forces, welcomed Hagel’s move.

“I remain concerned by the lapses in judgment and discipline displayed by some nuclear missile launch officers in recent months, and I applaud Defense Secretary Hagel’s swift and appropriate actions to identify the root causes of those issues,” Udall said. “Our nation demands a great deal of the men and women in our nuclear enterprise for good reason.”

Since May, the Associated Press has reported that nuclear force officers, from the commanding officer on down, had engaged in numerous misbehaviors. Some of those included failing security tests, violating security rules like leaving the blast door open while one of two officers napped, morale so low an officer complained of “rot” in his force and a report citing high levels of burnout.

Personnel issues are important because ICBMs are kept on alert every hour of every day, and the potential for human error is ever-present. Some argue that the men and women who hold the keys to the nuclear missiles have lost some of their focus on the mission, while others say their commanders are more to blame.

Not at issue, at least in the short term, is the Obama administration’s commitment to keeping the bulk of the current nuclear force, which is comprised of ballistic missile submarines, nuclear-capable bombers and the Air Force’s fleet of 450 Minuteman 3 intercontinental ballistic missiles based in silos in five states. Hagel recently reiterated his support for the nuclear force and said he is not questioning its safety.

Hagel directed his concern mainly at the Air Force and its Minuteman 3 missiles, which have been the source of many of the problems.

With an eye toward avoiding further surprises, Hagel’s planned Pentagon summit meeting with top officers, as well as other actions announced Thursday, include participation by Navy officials responsible for their portion of the nuclear arsenal. The Navy has not suffered any recent reported lapses or failures within its nuclear submarine force, but Kirby said Hagel believed it would be imprudent for him not to examine the entirety of the arsenal.