WASHINGTON – Top Army and Air Force officers said Tuesday they would be reluctant to overturn a 17-year policy that prohibits gays from serving openly in the military without more time to ascertain it won’t hurt the services.

”I do have serious concerns about the impact of a repeal of the law on a force that is fully engaged in two wars and has been at war for 81/2 years,” Army Chief of Staff Gen. George Casey told Congress. ”We just don’t know the impacts on readiness.”

As Casey cautioned the Senate Armed Services Committee against moving too fast to repeal the law, Air Force Chief of Staff Gen. Norton Schwartz made similar remarks before the House.

The carefully crafted comments show reluctance among the military’s senior ranks to act anytime soon on President Barack Obama’s plan to repeal the ”don’t ask, don’t tell” policy.

Obama says the policy is wrongheaded and should change. Defense Secretary Robert Gates agrees but wants to move slowly.