Every month at Punchbowl cemetery, about 16 veterans buried as “unknowns” from past conflicts are exhumed for identification and reburial by families — usually in a hometown cemetery.

That, in turn, is increasingly opening up rare in-ground burial space at the scenic veterans cemetery, which sits atop a volcanic crater and overlooks downtown Honolulu.

The National Memorial Cemetery of the Pacific, opened in 1949, has generally been full for in-ground burials for decades. Nearly 7,000 columbarium niches for cremated remains were added last year to the more than 13,000 that already existed.

But as the result of an ambitious effort by the Defense POW/MIA Accounting Agency over the past several years to exhume and identify service members from World War II and Korea, some grave-site space is opening up. Punchbowl has just under 30,000 grave sites.

The Defense Department agency, which has a lab and offices in Hawaii, investigates, recovers and identifies missing personnel from past wars.

“At any given time, on average, we may have three or four (grave sites) available” for burials, said cemetery Director Jim Horton.

That number sometimes drops to zero and not too long ago was as high as 10. The cemetery also retains three grave sites for service members who might be killed in action.

The open graves, meanwhile, “are being requested to be used as fast as they are coming in,” Horton said.

John Williams, commander of the American Legion Department of Hawaii, said interest in burial at Punchbowl remains high for World War II, Korea and Vietnam veterans.

“When we tell them they may not be eligible, it’s very disappointing,” Williams said.

In 2015 the Pentagon announced that it was taking the unprecedented step of exhuming all the USS Oklahoma’s remaining 388 crew members who died Dec. 7, 1941, and were buried as unknowns at Punchbowl.

The move came amid mounting pressure from Congress for the Defense POW/MIA Accounting Agency to increase its identifications from recoveries made overseas as well as from Punchbowl to at least 200 a year.

Since then all 94 caskets with unknowns from the 1943 Battle of Tarawa also have been exhumed so identifications can be made, and so have all 35 of the graves from the battleship USS West Virginia and 25 from the USS California, the agency said.

Lt. Col. Ken Hoffman, an agency spokesman, said 138 of the Oklahoma crew members have been identified. Twenty-four have been identified from the Tarawa group. Most families choose reburial in their hometowns.

The agency, with assistance from the Veterans Affairs cemetery, also has been disinterring unknowns from the Korean War. Advances in science, including DNA analysis, have made the identifications possible.

“DPAA is constantly researching cases for disinterment,” said Paul D. Emanovsky, laboratory manager-special projects for the agency. He added that approvals are being sought for cases originating from the China-Burma-India theater, the Northern Mariana Islands and others in Hawaii.

The agency made a record 201 individual identifications during fiscal year 2017.

Horton, Punchbowl’s director, said a few open grave sites are also reclaimed from a policy that ended in the early 1970s that provided for reserved space for a family. In many cases the military family moved out of Hawaii, and the graves weren’t used.

The cemetery annually goes through the list of those “couple hundred” grave reservations that remain, and “we get a few back here and there,” he said.

Horton said that when he took over as director in 2014, “we were only doing disinterments two or three or four and maybe once every other month” compared with the 16 per month now. Crews come in on Sundays and Mondays to do a formal transfer of remains.

The majority of the reclaimed grave sites are from DPAA identifications and reinterment elsewhere, he said.

Before Horton arrived the VA received criticism for not communicating widely the availability of in-ground graves. Horton said that has changed.

“We make sure that everybody from all of the veteran service organizations, everybody that we interact with, whether it’s congressional members or local, we’re constantly talking to them and telling them, ‘Hey, we’ve still got a few grave sites available,’” he said.

Those in-ground graves are now given out first come, first served to veterans.

“There are no reservations allowed,” Horton said. “There is no ‘Hey, I’m a four-star (officer), I trump this poor sergeant.’ There’s none of that.”