Threats to the US Defense Department personnel and facilities increasingly are coming from trusted insiders, and to defeat them the Pentagon must beef up security from within, according to several reviews triggered by last year’s Washington Navy Yard killings.

Threats to the US Defense Department personnel and facilities increasingly are coming from trusted insiders, and to defeat them the Pentagon must beef up security from within, according to several reviews triggered by last year’s Washington Navy Yard killings.

An independent study and an internal review ordered after the September 2013 massacre and released recently said the Pentagon must expand its focus beyond defending against external threats. More attention must be paid, they concluded, to defending against threats from inside the workforce.

According to the Navy probe, the Fort Lauderdale, Florida-based company, The Experts, pulled Alexis’ access to classified material because of concerns he was having mental health problems. It then restored his access two days later and never told the Navy about it.

The report written by Navy Admiral John Richardson said Alexis’s behaviour raised concerns among his supervisors and others and indicated he may harm others. Had such information been reported to the government and acted upon, it stated, Alexis’ authorisation to secure facilities would have been revoked.

Alexis’ company temporarily withdrew his access to classified information after a series of bizarre complaints and police incidents last August during a business trip to Newport, Rhode Islands. Alexis complained that people were following him, making noise and using a microwave machine to “send vibrations through the ceiling” in his hotel room.