Michelle Manhart defended her decision to pose

The move reverts Michelle Manhart to air national guard status, a move which has prompted her resignation, she says.

"I'm disappointed in our system. They went too far with it," she told the Associated Press news agency.

Ms Manhart appeared in the Playboy's February edition in a range of poses, some in uniform and striking a military pose, others while naked.

Ms Manhart had been a member of the Iowa air national guard before going on extended active duty with the air force.

In January, Ms Manhart was suspended from duties while an investigation into the incident was carried out.

At the time the air force released a statement saying that her actions did not "meet the high standards we expect of our airmen".

However, Ms Manhart defended her decision to pose for the magazine, pointing out that she had served her country since 1994.