The Pentagon's highest-ranking officials are preparing to make final decisions about whether to open all combat jobs to female service members.

It's been more than two years since then-Defense Secretary Leon Panetta stunned the military community by announcing plans to change the longstanding rule technically excluding women from serving in combat roles — more than 300,000 jobs in all, many of Army and Marine Corps infantry and armor units.

Now deadlines looming later this year will force the military's top brass to either clear a path to eliminate all gender restrictions, or serve up a good reason why not by requesting a formal waiver to the forcewide policy.

"We've really tried to give them the time that they need to finish their studies," said Juliet Beyler, the Pentagon's director of officer and enlisted personnel management, who is overseeing the process.

Any waiver request will land on Defense Secretary Ash Carter's desk and must be "based on a rigorous analysis of the knowledge, skills and abilities required to do the job," Beyler said in an interview.

Service chiefs will have to submit any waiver requests this fall for Carter's review before Jan. 1, when the new policy is due to take effect.

Since the three-year transition began in January 2013, the Army and Marine Corps have begun opening some career fields and billets previously restricted to men. The Army recently opened up combat engineer positions to women, while the Corps has lifted gender restrictions for ground intelligence officers.

In total, about 91,000 previously male-only jobs have been opened to women over the past few years. Across the active and reserve forces, about 240,000 jobs remain closed, mainly in infantry and armor units, defense officials said.

Special Operations Command is mounting its own independent review of the new policy to determine whether some of its jobs will remain closed. The new policy's impact on the Navy and the Air Force will be limited beyond special operations units, which is a decision that SOCOM will primarily address.

Meanwhile, the Army and Marine Corps have begun integrating women into their combat arms training programs.

In April, for the first time, the Army allowed 19 women to attend Army Ranger School. Eight completed the first training phase, but instructors did not allow them to advance into the second phase of Ranger training. Instead, those eight women will be able to try again and repeat the first phase.

Army Chief of Staff Gen. Ray Odierno said he expects the Ranger School to hold a few more coed courses later this year.

The Marine Corps recently completed an gender-integrated combat arms training program that let researchers study and compare the abilities of men and women to meet the physical challenges of the career fields. The Corps also has sent 27 female volunteers through its Infantry Officer Course, but none completed it, with most failing the grueling combat endurance test.

Both services say they will continue to evaluate the issue and draw up gender-neutral standards and requirements for each career field. They have made no final decisions about whether to seek an exemption to the new policy and try to keep some jobs, or specific billets, limited to men.

Yet subtle signals have emerged over the past two years to indicate the Army and Marine Corps are taking distinct approaches to the transition, said Ellen Haring, a retired Army colonel who studies the role of women in the military at George Mason University's School for Conflict Analysis and Resolution.

"I think the Army has approached this more as, 'how will we do this,' not 'whether we will do this.' And I think the Marine Corps' approach has been more of an investigation into whether we should do this," Haring said in a recent interview.

The two services could seek different policies. But that would be problematic because infantry jobs in the two branches are very similar. And the Pentagon also faces a lawsuit from former female troops who claim all restrictions for women amount to discrimination and are unconstitutional.

"They are going to be hard-pressed to reach different conclusions," Haring said.

The social and cultural differences between the services and their individual units will play a part in the final decisions, alongside the vast trove of physiological data and hard metrics that both services have compiled during the past two years.

"Certainly service culture plays a big part and that is normal and expected, but it is a consideration among many," Beyler said. "That is exactly why it's so critical that the review and the validation of the standards is so sound, that it is definitively tied to an operational requirement, that it is current, that it's reflective of what is necessary today, and, of course, gender-neutral.

"We needed to give the services time to review and validate those standards looking at it through their unique lens and depending on where they come out we'll see what they say," Beyler said.

Critics say the combat exclusion rule that restricted women from jobs with combat units at the battalion level and below, last revised in 1994, did not reflect the ground-level risks faced by all troops in Iraq and Afghanistan regardless of their designation as a "combat" unit. About 300,000 women served in the two wars and more than 150 were killed.

Critics also said the rule was harming women's career prospects in institutions where most of the senior leaders emerge from combat arms career fields.

Critics of the transition fear that introducing women into the tightly-knit combat world, especially the spec-ops teams that run in small formations, will erode unit performance through a toxic mix of traditional chivalry, gender bias and sexual tension.

Beyler said maintaining high standards for individuals will be the key to addressing those concerns.

"For a unit or an organization to achieve task cohesion, there has to be respect among each of the individuals on the team that each of them can do their job," she said. "If they believe that each member of the team can meet the requirements of doing their job and doing it will then you will have that cohesion.

"What it all boils down to is, at the end of the day, what is needed to do the job? And if somebody can do the job, they will get the respect from their peers that is necessary."

The truck which slammed into revelers late Thursday, July 14, is seen near the site of an attack in the French resort city of Nice, southern France, Friday, July 15, 2016. The truck loaded with weapons and hand grenades drove onto a sidewalk for more than a mile, plowing through Bastille Day revelers who'd gathered to watch fireworks in the French resort city of Nice late Thursday. (AP Photo/Luca Bruno)
The truck which slammed into revelers late Thursday, July 14, is seen near the site of an attack in the French resort city of Nice, southern France, Friday, July 15, 2016. The truck loaded with weapons and hand grenades drove onto a sidewalk for more than a mile, plowing through Bastille Day revelers who'd gathered to watch fireworks in the French resort city of Nice late Thursday. (AP Photo/Luca Bruno)