US Air Force Staff Sgt. Michelle Manhart poses with the February issue of Playboy magazine in San Antonio, Jan. 11, 2007. Manhart, who is featured in the February issue of Playboy magazine, has been relieved of her duties pending an investigation. [AP]

San Antonio - "Drop and give me 20!" is something you might hear Air Force Staff Sgt. Michelle Manhart yell to airmen trainees at Lackland Air Force Base. Drop her trousers is what Manhart did for Playboy magazine, and now it's landed her in trouble with the military.

"Of what I did, nothing is wrong so I didn't anticipate anything of course," Manhart said Thursday of the pictorial. "I didn't do anything wrong so I didn't think it would be a major issue."

In a six-page spread in February's issue, hitting newsstands this week, Manhart is photographed in uniform yelling and holding weapons under the headline "Tough Love." The following pages show her partially clothed wearing her dog tags while working out, as well as completely nude.

Manhart, 30, who is married with two children, has been relieved of her duties pending an investigation, according to Lackland AFB spokesman Oscar Balladares.

"This staff sergeant's alleged action does not meet the high standards we expect of our airmen, nor does it comply with the Air Force's core values of integrity, service before self, and excellence in all we do. It is not representative of the many thousands of outstanding airmen who serve in the US Air Force today," Balladares said, reading a statement.

Manhart has modeled since she was younger and joined the Air Force in 1994, spending time in Kuwait in 2002. The California native said she hopes the Playboy photo shoot will pave a way into an acting or modeling career.

The pictorial's accompanying article mentioned the possibility of trouble for the brunette drill instructor. But when asked in the article whether it might get her in "hot water with Uncle Sam," Manhart replied: "I've been serving for 13 years, fighting for everyone's rights. Why wouldn't I be able to stand up for my own rights and participate in the freedoms that make this country what it is?"

Manhart said she didn't see the magazine as an escape from the military. She also said she is completely committed to her job.

"I've proven myself. ... They picked me to train our future airmen of the world," she said. "They picked me to train these individuals so if they elect to say I don't have (integrity) then that's their opinion."

Playboy magazine spokeswoman Theresa Hennessey said two active-duty women have posed nude in Playboy in the past. Both were in the Navy, she said.

One, Sherry Lynne White, was discharged in July 2000 after posing nude for the magazine. She had been scheduled to be released from duty that October.

Another, Frederica Spilman, received an honorable discharge, which she had sought before posing, and a letter expressing the Navy's dismay less than a week after the June 1998 issue hit newsstands.

Spilman appeared in the magazine wearing opened flight jackets, camouflage lingerie and dog tags. The six-page pictorial, under the heading "Fly Girl," also included pictures of Spilman in her Navy uniform and flight suit.

Hennessey added that seven women also were featured in a "Women of the Armed Forces" spread in April 1980.

Manhart said the shoot came about after she went on a casting call and kept getting called back for test shots. The February pictorial was shot last spring, she said.

"The Air Force says go do something amazing, and I think I pretty much did it," she said.