The slate of proposed changes to military pay and benefits is facing a new round of criticism for failing to fully tackle the long-term problems confronting the military personnel system.

For months, the Military Compensation and Retirement Modernization Commission's recommendations for reform were scorned by veterans groups that claimed the proposals were too aggressive and threatened retention.

Now some military personnel experts are lodging the opposite critique.

"The commission did not go far enough," said Arnold Punaro, a retired Marine major general and chairman of the Reserve Forces Policy Board, a Pentagon advisory group.

Punaro joined other military personnel experts and former officers at the Center for American Progress in Washington on Thursday. They offered similar views that the commission's recommendations, particularly the proposed changes to the retirement system, fail to sufficiently cut manpower costs or lay a substantive foundation for a modern, flexible force of the future.

"I think the commission stepped up to the plate and hoped to hit a home run [but] they probably hit about a double, maybe a triple," said Phil Carter, a former Army officer and Iraq veteran who heads the Military, Veterans and Society Program at the Center for a New American Security.

"They had a mandate to think about the all-volunteer force and its future and really grapple with the social contract and what we really owe those who serve and their families," Carter said. "What they ended up producing is a set of narrow recommendations … to tweak our social contract."

The compensation commission, created by Congress two years ago, issued 15 recommendations in its report released in January. Among them was a retirement reform proposal that would shrink by 20 percent the current pension for those who stay for 20 years or more, while also making government contributions to individual investment accounts for all troops, even those who serve less than 20 years.

Lawmakers have voiced support for the retirement reform proposal and a version of the plan has been included in the House Armed Services Committee's 2016 defense authorization bill. It could become law later this year.

Larry Korb, a former Pentagon personnel chief who is a defense expert at the Center for American Progress, offered nominal support for the recommendations and used a baseball analogy similar to Carter's.

"The commission was OK. I don't know if I'd give them a double. Maybe I'd give them a single," Korb said during the panel discussion.

But the cost of military personnel remains too high, Korb said. Unless the Defense Department and Congress make more dramatic reductions, the military will have no choice but to continually cut the total number of troops.

"If we are just going to keep going, you're going to have a smaller and smaller force to deal with the challenges we face," Korb said.

Punaro agreed. "The long-term, fully burdened and life-cycle costs of the all-volunteer force are basically unsustainable," he said, pointing to the history of the military since the 1980s, an era in which the size of the force has declined even as the military's per-troop costs have increased.

"We have fewer carriers, fewer tactical fighters, fewer bombers, fewer Army divisions, fewer Marine regiments than we've had because of the astronomical costs of personnel," Punaro concluded.