Secretary of Defense Chuck Hagel announced Wednesday details of a worldwide review of U.S. defense facilities after consulting with military leaders in response to a gun attack in which troubled former Navy reservist Aaron Alexis, who had site clearance at the Washington Navy Yard, entered the facility Monday and shot and killed 12 people.
Speaking at a news conference at the Pentagon, Hagel said he has ordered the Pentagon to review the physical security of all U.S. defense facilities worldwide and the security clearances that allow access to them.
The defense secretary is also tasking an independent panel to undertake the same reviews. He said Wednesday that "where there are gaps, we will close them."
Hagel also acknowledged that there is "some jeopardy" with long-lasting security clearances.
Meanwhile, the White House called for a review of the hiring procedures for private contractors at government offices.
"I can tell you that at the president's direction, (Office of Management and Budget) is examining standards for contractors and employees across federal agencies," White House Press Secretary Jay Carney said at a news briefing. "This is obviously a matter that the president believes and has believed merits review."
The Office of Personnel & Management, meanwhile, said that it conducted the background security clearance investigation for Alexis in 2007 and that the Department of Defense granted his security clearance in 2008.
The director of national intelligence, James Clapper, launched a review of security clearance policy for certain contractors Tuesday as well, Carney said.
The reviews come as investigators question how Alexis -- who had a string of run-ins with the law -- was able to get clearance to enter the Navy Yard, where he carried out Monday’s gun attack before being shot himself. It emerged Tuesday that police were aware of mental health issues relating to Alexis, whom it is believed to have suffered from paranoia and heard voices.
The DOD review into access at military sites comes on the back of the release of a year-long audit of the Naval security system (PDF) Tuesday that indicated that 52 convicted felons have had routine, unauthorized access to Navy facilities.
The FBI said that they believe Alexis entered Building 197 at the facility -- with a valid pass -- carrying a shotgun he legally bought. The bureau also said it believes the suspected shooter obtained a handgun once inside.
It is believed that Alexis was able to buy the firearm from a registered gun shop despite having had known mental health issues. Police in Newport, R.I., say they contacted Naval Police after Alexis wanted to file a harassment report, claiming that three people were following him, talking to him through his hotel walls and "sending vibrations into his body," according to a police report.
U.S. law-enforcement officials told The Associated Press Tuesday the alleged gunman suffered from paranoia and a sleep disorder and was occasionally prone to flashes of rage.
Family members told investigators Monday that Alexis had been treated for mental-health issues since August by the Department of Veterans Affairs, officials said.
Authorities believe that Alexis arrived in Washington on Aug. 25, and had been staying at local hotels prior to Monday's attack. Just one day before the Navy Yard shooting, the suspect visited a gun range in Virginia.
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Since the shooting, details of the alleged shooter's military record have emerged. The former reservist received an early -- but honorable -- discharge from the Navy Reserve in 2011, despite having exhibited a pattern of misconduct during his career, a Navy official said Tuesday.
Before issuing the honorable discharge, however, the Navy had pursued a general discharge after eight to 10 misconduct charges were filed against Alexis ranging from traffic offenses to disorderly conduct, according to Navy officials.
The Navy had not declared Alexis mentally unfit, which would have rescinded a security clearance that he had from his time in the Navy Reserve. But officials described Alexis' four-year stint in the Navy, from 2007 to 2011, as troubled.
He was arrested on Sept. 4, 2010, in Fort Worth, Texas, on a misdemeanor charge of discharging a firearm. The case was dropped when investigators determined he was cleaning his gun before it accidentally fired, Tarrant County prosecutors said.
He was also arrested in Seattle in 2004 for shooting a construction worker's car tires in what Alexis described as an anger-fueled "blackout," according to the Seattle Police Department.
But no motive for the Navy Yard shooting has emerged and Alexis "never sought an appointment from mental health specialists," according to the Department of Veterans Affairs.
Meanwhile on Wednesday, the mother of Alexis apologized to the families of the victims in an audio recording and said she does not know why her son "did what he did and I'll never be able to ask him why."
"Aaron is now in a place where he can no longer do harm to anyone, and for that, I am glad," Cathleen Alexis added.
Al Jazeera and wire services with Wilson Dizard reporting from Washington.