The top defense policy Republican in the Senate threatened Thursday to introduce legislation that would attempt to block part of the Pentagon’s initiative to lift the ban on women in combat after the changes were officially announced.

“If necessary, we will be able to introduce legislation to stop any changes we believe to be detrimental to our fighting forces and capabilities,” Sen. James M. Inhofe, R-Okla., ranking Republican on the Armed Services Committee, said in a written statement. “I suspect there will be cases where legislation becomes necessary.”

The Senate is dominated by Democrats, virtually assuring the historic changes ordered by the Pentagon will be implemented over time. But Inhofe’s statement reflects the views of a segment — though not all — of the GOP that objects to some of the social changes being made in the military.

Notably, Sen. John McCain of Arizona, who just stepped down as the ranking Republican on the Armed Services panel, welcomed the move.

“I respect and support Secretary [Leon E.] Panetta’s decision to lift the ban on women serving in combat,” he said in a written statement late Wednesday. “As this new rule is implemented, it is critical that we maintain the same high standards that have made the American military the most feared and admired fighting force in the world — particularly the rigorous physical standards for our elite special forces units.”

Lifting the combat ban opens up more opportunities for advancement and earnings for female service members, which could significantly alter the male-dominated military culture. Currently, there is only one four-star female military officer.

Defense Secretary Panetta and Army Gen. Martin E. Dempsey, in announcing their intentions to lift the ban on women serving in combat roles, said Thursday that women make up 15 percent of the total forces or about 200,000.

“They’re serving in a growing number of critical roles on and off the battlefield,” Panetta said. “The fact is that they have become an integral part of our ability to perform our mission.”

The Pentagon must notify the defense policy panels no less than 30 days before such a change is made. That leaves Congress with a small window of time to try to block the changes.

The decision announced by Panetta and Dempsey has grown out of shifting wartime dynamics that have already seen many women on the front lines. In Iraq and Afghanistan, 152 women in uniform have died, and more than 800 have been wounded.

“Female servicemembers have faced the reality of combat, proven their willingness to fight and, yes, to die to defend their fellow Americans,” Panetta said.

But citing some of the same reasons he presented in opposing the repeal of the ban on gays and lesbians serving openly in the military, Inhofe said he is concerned about making changes that might disrupt the force.

“Because that policy has worked so well for so long, I am concerned about the potential impacts of completely ending this policy,” Inhofe said.

He noted that while the Pentagon has rescinded the 1994 direct-combat definition and assignment rule, not all of the 237,000 positions previously closed to women will now be automatically open to women.

“Instead, the military services, under Secretary Panetta’s direction, will conduct a review of all unit and specialty positions to be completed no later than 2016,” Inhofe said.

Indeed, the Pentagon in a statement said Panetta directed the military departments to submit detailed plans by May 15 for the implementation of this change. This process will be completed by Jan. 1, 2016.

But Panetta said that changes made in 2012 that opened more than 14,000 new positions to women, including positions collocated with ground combat units and in some combat units below the battalion level, have reaped positive outcomes and affirm the need for change.

Panetta said he had no intention of lowering standards or qualifications in any way. Under law (PL 103-160), occupational performance standards must be gender-neutral, the Pentagon said.

“If they can meet the qualifications for the job, then they should have the right to serve, regardless of creed or color or gender or sexual orientation,” Panetta said.

Loretta Sanchez, D-Calif., a senior member of the House Armed Services Committee, lauded the decision and noted that the military timeline for the changes was “ambitious.”

“Congress is here to help where we can,” she said in a statement. “Ultimately, it is the sacrifice and dedication of the service women that has brought about this historic change.”

In a written statement, President Barack Obama praised the Pentagon’s decision.

“As commander in chief, I am absolutely confident that — as with the repeal of ‘Don’t Ask Don’t Tell’ — the professionalism of our armed forces will ensure a smooth transition and keep our military the very best in the world,” he said.

The decision has the unanimous support of the Joint Chiefs of Staff.