Defense Secretary Robert Gates on Thursday reassured U.S. warfighters in Iraq that allowing gays to serve openly in the military will have little impact on the armed forces, an argument largely echoed by the top leaders of the Army, Air Force, Marines and Navy.

Visiting troops at Camp Liberty in Baghdad, Gates was asked when repeal of the 17-year-old policy commonly known as "don't ask, don't tell" would occur and what its effect would be.

"My guess is you won't see much change at all because the whole thrust of the training is you're supposed to go on treating everybody like you're supposed to be treating everybody now, with dignity, respect and discipline," Gates told the troops. "And the same kind of military discipline that applies to — and regulations that apply to heterosexual relationships — will apply in terms of homosexual relationships."

In Washington, leaders from the four services testified before the House Armed Services Committee on the implementation of the new policy. Several expressed reservations last December when a divided Congress voted to repeal the law and President Barack Obama signed the legislation.

The repeal did not occur immediately as training and certification by the department were required before the ban is lifted. Training for the service members began around March 1 and is slated to be finished by summer's end.

Gen. James Amos, commandant of the Marine Corps, had testified last year that permitting gays to serve openly could disrupt smaller combat units and distract leadership from preparing Marines for battle. On Thursday, Amos said during a recent trip to Afghanistan, he was specifically looking for problems that might arise.

"There hasn't been the recalcitrant push back, not been the anxiety of the forces in field," Amos told the committee. He said one commander told him troops are focused on the enemy.

Last year, Gen. Norton Schwartz, chief of staff of the Air Force, had recommended waiting until 2012 to implement the new policy.

"We're mitigating the risk the way we're approaching this," Schwartz said Thursday. He added he was more comfortable with the policy now than he was last December.

Adm. Gary Roughead, the chief of Naval Operations, said training was going well and the "type of questions reflect the professionalism and the maturity and the decency of our people."

Gen. Peter Chiarelli, vice chief of staff of the Army, said he met with commanders last Friday and "they indicated no issues so far."

Nevertheless, Republicans on the committee have been critical of the policy change, with Chairman Rep. Howard "Buck" McKeon of California calling it a "rush to judgment."

"The one outcome that must be avoided is any course of action that would put the combat readiness of our military forces at risk," McKeon said.

Rep. Adam Smith of Washington state, the top Democrat on the panel, countered that forcing service members out of the military based simply on sexual orientation is far more disruptive.

"Gays and lesbians are currently serving in our armed forces, and we have the strongest military in the world," Smith said. "Driving thousands of qualified individuals out of our armed forces under "don't ask, don't tell" undermines our military's effectiveness."

Pressed by Republicans on the implications of the change, senior military leaders insisted the services would be able to retain talented members and it could potentially increase the pool of recruits.

"We will see good people serving," Roughead said.

Amos said it would "increase peace of mind for gays and lesbians in the Marines."

Rep. Vicky Hartzler, R-Mo., pleaded with the military leaders: "You are the last force to stop this onerous policy."

In a statement, Servicemembers United, an organization of gay and lesbian troops, said the "issue has been settled, the Department of Defense has embraced this change and trying to re-open this debate is a waste of both taxpayer money and the valuable time of these senior defense leaders in the midst of multiple overseas conflicts."

In fact, the hearing was interrupted for more than an hour for votes in the House and the senior military leaders had to wait before resuming their testimony.


AP National Security Writer Robert Burns in Baghdad contributed to this report.