FORT BRAGG, N.C. — After the 9/11 attacks, tens of thousands of young men and women joined the military, heading for the rugged mountains of Afghanistan and dusty deserts of Iraq.

Many of them now are officers in the Army with multiple combat deployments under their belts. But as the wars wind down and Pentagon budgets shrink, a lot of them are being told they have to leave.

It's painful and frustrating. In quiet conversations at Fort Bragg in North Carolina and Fort Eustis in Virginia, captains talk about their new worries after 15-month deployments in which they battled insurgents and saw roadside bombs kill and maim their comrades. They nervously wait as their fates rest in the hands of evaluation boards that may spend only a few minutes reading through service records before making decisions that could end careers.

During the peak war years, the Army grew to about 570,000, as commanders worked to fill combat brigades and support units to fight in Iraq and Afghanistan. Thousands of newly minted officers came in during 2006-2008.

Already down to about 522,000, the Army must shrink to 490,000 by October 2015, and then to 450,000 two years later. If automatic budget cuts resume, the Army will have to get down to 420,000 — a size service leaders say may not allow them to wage even one major, prolonged military campaign.

While a lot of the reduction can come from voluntary retirements, resignations and decreased enlistments, Army commanders will have to force as many as 3,000 officers — nearly 10 percent of the planned decrease — to leave by the end of October 2015. Of those, nearly 1,500 are captains, 550 are majors.

Behind some of those big numbers are soldiers in their late 20s who will be forced out of their military careers long before retirement age and into the still struggling American job market. They would leave with honorable discharges, but without 20 years in the service they would not be eligible for retirement benefits.

"The captains are a problem," Gen. Ray Odierno, the Army chief of staff, said in a recent interview with The Associated Press. "Because when we increased the size of the Army we recruited heavily in certain year groups. So as we draw the Army down, those are over strength."

The military has been through this before. In the years after Vietnam and during the 1990s as the Cold War thawed, the Pentagon pushed thousands of service members out the door, creating what some felt was a hollow military that lacked the soldiers, training and equipment needed to fight and win.

This time, Army leaders argue they're trying to do it right. They're not asking for volunteers, because too many good people leave. So they are combing through files, looking for soldiers with disciplinary or other problems in their annual evaluations — known as efficiency reports — to weed out lower-performing officers.

Col. Trevor Bredenkamp, commander of the 82nd Airborne Division's 1st Brigade Combat Team, said he talked to all of his majors who were in that group, and he had his battalion commanders talk to their captains.

"The challenge is there are about 8 percent that they will have to select that don't have any derogatory information in their file. So there will be some people that will say I don't know why I was selected," Bredenkamp said. "I'm telling people, hey, they're going to decide who they decide on, and if you've been working hard and doing a good job, by and large, the majority of you don't have to worry about it."

Capt. Fred Janoe, a battery commander with the 18th Fires Brigade at Fort Bragg, said the process may create a short-term decline in morale but will be positive in the long term.

"You keep your best performers and as an organization you're able to do more with less," Janoe said.

Sometimes, he said, "you see guys who just barely get by. I don't wish for anything bad to happen to them." But he added, "I grew up on a cattle ranch, and sometimes you cull the herd a little bit."

Other captains did not publicly discuss their concerns about impending separation. But there are broad concerns that when the young officers were serving in Iraq and Afghanistan during the peak war years, the attention paid to their evaluations may have slipped a bit and many of them got largely the same positive ratings. Some worry that a less than stellar relationship with one senior officer may doom their relatively short careers, while others say many lower performers got high marks while deployed, skewing the system.

Some officers have even found themselves in the odd position of being up for a promotion at the same time as they are being considered for separation, with both evaluation boards going on at about the same time.

Odierno said he recognizes the concerns and the Army is trying to go through the process carefully once it gets to the officers who don't have problems in their files.

"We're doing that a bit slower. I want to make sure that they have enough years where we can do a proper evaluation," he said. "We want to keep the best. We want it to be very competitive."

Once chosen for departure, the young officers will have two months to leave.

"We have an obligation to help them land softly on the outside of the Army," said Bredenkamp.