WASHINGTON — He wore a short-sleeved Navy summer white uniform, crisp and pressed. Had the black and gold shoulder boards of a rear admiral and a chest full of ribbons and carried himself with the confidence such a rank bestows.

He said he was a veteran who had served all over the world, in Afghanistan, Kosovo, Iraq.

Last year, at a ceremony in Falls Church, Va., to commemorate the Republic of Vietnam's Armed Forces Day, Trung Huan Nguyen took the stage and addressed a crowd of about 100 Vietnamese Americans.

There was something not quite right about the man in white. No matter how perfect his uniform, or plentiful his service and personal decoration ribbons, some attendees were suspicious. They checked him out. And last week, Nguyen pleaded guilty in U.S. District Court in Alexandria, Va., to impersonating a Navy rear admiral.

In truth, Nguyen, of Middletown, Del., was never more than an enlisted man and had been out of the Navy for 13 years.

Prosecutors said Nguyen's deceit went beyond merely playing the part of a highly ranked officer at the event in June 2007. They said he put a profile on the Web site military.com that claimed he was commissioned into the Navy as a medical doctor in 1985 and received special warfare training.

In his online biography, he played up his combat experience and said he had served in the Gulf War and the Iraq war.

The reality, prosecutors said, was that he had been an E-4, a petty officer third class, the equivalent of an Army corporal. He served aboard the USS Missouri and USS Constellation and at the Naval Air Station at North Island in San Diego.

His Navy career lasted just four years and he left with an honorable discharge.

Lawyer David Hubbard said his client told the judge that he had always wanted to be a naval officer and could never get over the disappointment of not realizing his dream.

"I think that he very much wanted to be in the officer corps and that despite his best efforts, he was disappointed that he never made it," Hubbard said.

Hubbard could not say why the military rejected Nguyen's request to join the ranks of officers but noted that he was honorably discharged.

He said Nguyen, who is in his early 40s, came to the United States from Vietnam and "joined the military as a way to fit in in society, to find a place in America."

The lawyer added that Nguyen apologized to the judge and is "very sorry for what he has done."

The Naval Criminal Investigative Service investigated the case, and now Nguyen is facing up to three years in prison and a $250,000 fine.

He was released on a personal recognizance bond.

As part of his plea, he agreed to turn over any uniforms, insignias and decorations he is not entitled to.

He is also required to send in a "mental health evaluation and treatment and waive all confidentiality," according to court documents.