The move follows a 45-day review of Defense Department policies and procedures that Austin ordered after a junior airman allegedly orchestrated the most damaging leak of US classified documents in a decade.

"The review identified areas where we can and must improve accountability measures to prevent the compromise of CNSI (classified national security information), to include addressing insider threats," Austin wrote in a memo released by the Pentagon.

Steps assigned by Austin include developing a plan for a so-called Joint Management Office for Insider Threat and Cyber Capabilities to "improve threat monitoring across all (Pentagon) networks."

He also called for guidance to be issued to "immediately enhance accountability and control of top secret information," and for the implementation of a "phased approach to increase accountability, manage access, and increase security to classified data."

Jack Teixeira, a 21-year-old Massachusetts Air National Guard IT specialist, was arrested in April after allegedly posting a series of highly sensitive documents to a private chat group on social media platform Discord.

The documents, which soon spread across the internet, pointed to US concern over Ukraine's military capacity against invading Russian forces and showed Washington had apparently spied on allies Israel and South Korea, among other sensitive details.

It was the biggest such breach since the 2013 dump of National Security Agency documents by Edward Snowden and raised tough questions about access by Teixeira, a junior staffer, to high-level secrets.

Teixeira -- who pleaded not guilty last month -- is facing six counts of retaining and transmitting national defense information, which each carry sentences of up to 10 years in prison.