WASHINGTON - The US military celebrated gay pride month at the Pentagon for the first time on Tuesday, with officials praising the services for smoothly adapting to a law that permits homosexuals to serve openly in the armed forces.

"As recently as three years ago, it would have been hard for many of us, including me, to believe that in the year 2012, a gay man or woman in the armed forces could be honest about their sexual orientation," the Pentagon's top lawyer, Jeh Johnson, said in a keynote address.

"How has the military accepted this change? Better than we anticipated," he said. "I attribute this to the strength of our military and its army, navy, air force, marine and coast guard leadership."

However, some in the standing-room-only crowd of more than 400 at a Pentagon auditorium expressed concern at the spotty attendance by senior leaders from the different military services, saying it sent the wrong signal.

"I'm disappointed that the uniformed leadership didn't lead on this," said one officer who asked not to be identified. "Nobody would be required to come to this thing ... but I do think it would be a nice gesture. If you want to talk leadership, then lead."

The officer said senior uniformed commanders seemed to resistant to the gay pride event, even though similar celebrations have been held for years at other agencies, including the CIA, where they have been going on for 12 years.

The service leaders appeared to be conducting a "sort of silent protest," the officer said. "There's got to be. Nobody from the services' senior staff? No one?"

Panetta's pride

Defense Secretary Leon Panetta spoke to the gathering in a video message, praising gay and lesbian service members for serving with "professionalism and courage" even before the repeal of the "Don't Ask, Don't Tell" law last September.

"I am very proud of how we implemented repeal. Going forward, I remain committed to removing as many barriers as possible to make America's military a model of equal opportunity," Panetta said.

Under the Don't Ask, Don't Tell law, homosexuals were allowed to serve in the military so long as they did not divulge their sexual orientation.

Johnson told the group the decision to allow homosexuals to serve openly was not a foregone conclusion in 2010, when he and General Carter Ham, then the commander of the US army in Europe and currently head of US Africa Command, began a lengthy review of the policy.

"I think we actually saw attitudes shift as we stirred the pot on this issue," he said. "We had the overwhelming sense that with proper education and leadership, the military could be ready for this change."

"From those service members who are gay and lesbian, we lifted a real and personal burden from their shoulders," Johnson said. "They no longer have to live a lie in the military."

Marine Corps Captain Matthew Phelps, who is gay, told the crowd how difficult it was to live under Don't Ask, Don't Tell when he served in Iraq. During gatherings of his colleagues, they would talk about loved ones back home.

"I sat there ... not talking to anybody," he said. "When everybody was getting together and growing closer as a unit, by virtue of the fact that I wasn't allowed to say anything, I was actually growing more distant from my unit."

He said he believed the repeal of the law had actually improved the ability of military units to work together and support each other.

"We hear people talk about unit cohesion and how is the repeal of Don't Ask, Don't Tell going to affect unit cohesion," he said. "I would argue that it got better because now you have a whole portion of the military who is able to be honest with the people that they work with."