The gunman who killed 12 people at the Washington Navy Yard was "being treated for mental illness and was left 'devastated after his Thai girlfriend dumped him when she refused to move to the US,'" according to a report by UK's Daily Mail.
Daily Mail reported that Alexis, 34, sought treatment from the Veterans Administration for paranoia, insomnia and possible schizophrenia just one month before his shooting rampage.
The gunman, who was killed in an exchange of fire with police, was as a former sailor turned defense contractor with a history of disciplinary problems and run-ins with the law.
US authorities said the suspect, Aaron Alexis, 34, had entered the heavily-guarded Navy Yard with a valid security pass.
Navy secretary Ray Mabus said in a tweet that he had ordered the review for all bases "in the US to ensure we live up to our responsibility of taking care of our people."
The move came as the military faced tough questions in the wake of Monday's rampage at the Navy Yard, in the heart of the US capital.
The Navy plans two "physical security reviews," a naval official said, speaking on condition of anonymity.
The first would examine installations "to ensure that the physical security standards currently in place are being maintained."
The second review will look at "physical security to ensure correct security requirements are being implemented."
But the effort apparently will not look at vetting for the security clearances issued to defense contractors, despite a new internal Pentagon audit that found serious shortcomings.
The Defense Department inspector general's report, which was released to members of Congress on Monday, alleges the Navy botched security controls at many of its bases – including the Navy Yard – in a bid to save costs, said a defense official. READ: Hospital says three victims in critical condition
The audit, which was first reported by Time magazine, found 52 convicted felons had been granted access to naval posts due to faulty procedures.
At seven of 10 installations, the Navy failed to provide adequate resources to allow the bases to conduct proper background checks on outside contractors, according to the report, quoted by the defense official.
"The report details critical flaws in the practice of contracting access control for military installations to non-governmental personnel," said Buck McKeon, the Republican chairman of the House Armed Services Committee.
Pentagon chief Chuck Hagel "will likely order a review of the findings," the defense official told AFP. READ: 'Cowardly act' at Navy Yard kills patriots: Obama
Navy officials said the inspector general's report would be closely examined but might not be relevant to the Navy Yard rampage.
Even before the shooting, lawmakers had voiced concern over background checks for outside contractors after Edward Snowden, a former US intelligence subcontractor for Booz Allen, spilled National Security Agency secrets to newspapers that revealed America's far-reaching electronic surveillance of phone records and online traffic.
Critics have questioned why the young, relatively inexperienced IT subcontractor was allowed access to highly sensitive information.
(With inputs from AFP)