Maj. Gen. John O'Connor, commander of the 21st Theater Sustainment Command, left, and Maj. Gen. Laurian Anastasof, chief of the Romanian air force staff, cut the ribbon Friday, Feb. 28, 2014, at the new U.S. transit center at Mihail Kogalniceanu Air Base near Constanta, Romania.

MK AIR BASE, Romania — A temporary U.S. base in Romania that will serve as the primary hub for American forces leaving Afghanistan officially reached its full operating capacity Friday.

Since Feb. 2, some 6,000 American servicemembers have transited through the center at Mihail Kogalniceanu Air Base, located about 25 miles northwest of the Black Sea city of Constanta and about 2,500 miles northwest of Afghanistan.

“It’s an ideal location for us as far as capability,” Maj. Gen. John O’Connor, commander of the 21st Theater Sustainment Command said in a recent interview with Stars and Stripes.

The U.S. had already constructed 85 buildings capable of supporting roughly 1,500 personnel at Mihail Kogalniceanu – or MK Air Base – for previous missions, O’Connor said.

Beginning in late December, elements of the 21st expanded the infrastructure to accommodate up to 2,000 transiting troops and 400 military personnel who run the operation.

A ribbon cutting ceremony Friday in a processing tent built on a parking lot adjacent to the airstrip signaled that the base is ready to handle the full flow of troops in and out of Afghanistan.

The center replaces the transit center at Manas, Kyrgyzstan, which had processed hundreds of thousands of troops to and from the war beginning in the weeks after Sept. 11, 2001.

The Kyrgyz government last year declined to extend its lease on Manas, forcing the U.S. to find another location to stage its forces.

After previous threats by the Kyrgyz government to close the Manas operation, the U.S. started testing the possibility of shifting transit operations to Romania, O’Connor said. Some 20,000 U.S. troops from the United States and Germany transited through MK Air Base on their way to Afghanistan in the two years prior to the transit center’s opening in early February, he said. Those troop movements helped military planners decide how much additional infrastructure the Army needed to install at the base to handle the full flow of troops to and from Afghanistan.

The first flight of roughly 300 soldiers in the newly expanded MK transit center arrived Feb. 2.

On Friday, about 1,800 in-transit troops were bedded down in a living area a short drive from the processing center. Reporters who attended the ribbon-cutting ceremony didn’t see this portion of the base.

“It’s been really busy,” said Pfc. Bryan Orlando, a human resources specialist from Waterford, Calif., who helps process transiting personnel. “We’ve been getting a lot of flights.”

O’Connor said four C-17 transport planes and up to four commercial wide-body aircraft will ferry troops in and out of the center daily — about half going to Afghanistan, half home.

But for nearly three weeks after reaching its initial operating capacity in early February, only troops heading to the war transited through here. For about the last week, the flow has been going both ways.

“So we’re definitely seeing the op-tempo pick up,” Sgt. Bart Khan, a human resources specialist deployed here from Joint Base Lewis-McChord in Washington, said.

Construction of the additional tents and buildings to house and feed 2,000 transiting personnel, and contracts for cooks, trash and other base operations cost roughly $11 million, O’Connor said. The cost of running the base for the 10 months between now and the withdrawal of all combat troops from Afghanistan is estimated at between $18 million to $20 million, he said.

If the U.S. had had to build the entire base from scratch, O’Connor said, the cost likely would have exceeded $100 million.

The transit center’s primary purpose right now is to facilitate movement of personnel. But it is also on standby to handle equipment if other transportation routes, such as those from Afghanistan through Pakistan, are shut down or overwhelmed, O’Connor said.

The 400 personnel running the operation at MK are roughly a third as many as were running the base at Manas, O’Connor said.

However, Manas had other missions besides troop transport; it also hosted a fleet of refueling planes used to gas up military aircraft flying over Afghanistan, but that mission is also over.

The last KC-135 tanker landed at Manas on Feb. 24, after refueling A-10 Thunderbolt IIs and F-16 Fighting Falcons flying sorties over Afghanistan, according to the Air Force.

Email: millham.matthew@stripes.com

Twitter: @mattmillham