A retired army officer has quit working for Defence Minister David Johnston just three weeks after being hired to advise on a review into the nation's long-term defence policy.

Retired major-general Jim Molan, who helped the coalition author its policy to stop the flow of asylum seeker boats, has made it clear the minister, David Johnston, was the cause of his sudden resignation.

Retired major-general Jim Molan has quit the office of the Defence Minister, David Johnston, after only three weeks. Credit:Jeffrey Chan

General Molan told the Ten Network he "accepted a request" from the Defence Minister to advise on the Defence white paper, to be published next year, which helps inform the next decade's defence policy and strategy.

"It took me three weeks, unfortunately, to realised that this was not feasible," he told Channel Ten's The Bolt Report. The retired major-general made it clear that that no one in the force or the Defence Department was to blame for his departure.