WASHINGTON (AP) — Defense Secretary Chuck Hagel is ordering the Pentagon to review the physical security of all U.S. defense facilities worldwide and the security clearances that allow access to them.

Hagel is also tasking an independent panel to undertake the same reviews. He said Wednesday that "where there are gaps, we will close them."

Hagel ordered the reviews in response to Monday's shooting rampage at the Washington Navy Yard, where a dozen people were killed. The shooter, Aaron Alexis, was also killed.

Alexis, a former Navy reservist, had been undergoing mental health treatment from the Department of Veterans Affairs since August but was not stripped of his security clearance. The assault is raising more questions about the adequacy of the background checks done on contract employees.

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