An MV-22B Osprey carrying U.S. Marines prepares to leave Naval Air Station Sigonella, Italy, to escort approximately 150 personnel from the U.S. Embassy in Tripoli, Libya, on the morning of July 26, 2014. (Cpl. Shawn Valosin/U.S. Marine Corps)

Marines in Libya ahead of the July 26 evacuation of the U.S. Embassy in Tripoli expressed concern about using a ground convoy instead of aircraft to leave the country amid  violence, but acquiesced to the plan favored by Ambassador Deborah K. Jones, they said Thursday.

The mission withdrew at least 156 military and diplomatic personnel from compounds that had recently received upgrades prompted by the September 2012 attacks on U.S. compounds in the Libyan city of Benghazi that killed U.S. Ambassador J. Christopher Stevens and three other Americans.

The operation highlights the complicated planning required between the military and the State Department, especially following the Benghazi attacks and the proliferation of militant groups across northern Africa.

Col. Kenneth M. DeTreux, who led the Marine Corps’ crisis-response task force for the region, said Thursday that he favored an aerial evacuation, but could understand Jones’s concerns about showing a large military presence while pulling out. The withdrawal came as fighting between Libyan militias threatened the U.S. facilities, one of which had been hit by a mortar round, Marines said.

“I would have done something different, and it would have been just as successful,” DeTreux said Thursday at the Pentagon. “But it was her call for a ground convoy movement, and I think as a military guy you understand that there will be political and diplomatic lenses that are being looked through. We just have to remain flexible, agile and responsive, and I think that’s what we did in this case.”

This map shows the July 26 evacuation of military and diplomatic personnel from the U.S. Embassy in Tripoli amid clashes between local militias that threatened their safety. (U.S. Marine Corps)

A State Department official familiar with the ambassador’s thinking said she saw the ground convoy as the most practical option to minimize risk in an area where rockets and mortars were being fired regularly. U.S. officials also had reached a deal with two local militias to allow U.S. personnel safe passage, and it would allow the United States to recover numerous armored vehicles, which are valued at about $250,000 each.

The ambassador also was concerned about a lack of clarity she saw in how the aerial evacuation would have been pursued, the source said. U.S. options were curtailed in part because fighting between the militias had closed the airport in Tripoli just days before. Without it, it’s likely that the United States could have withdrawn only what could be carried by helicopters.

The evacuation ultimately rolled through Libya with 39 armored Chevy Suburban and Toyota 4Runner sports utility vehicles owned by the State Department. It began early July 26 and continued for more than six hours northwest before crossing the border into Tunisia without major incident, Marines involved said.

There were concerns, however. While an agreement had been reached with the militias near the Tunisian border, there were still concerns that a fighter along the road somewhere did not receive the message and would have opened fire, said Capt. Jim Oliveto, commander of India Company, 3rd Battalion, 8th Marines, the unit deployed at the embassy at the time to provide security. The Marines wore civilian clothes with their body armor at the request of the State Department to keep a lower profile, he said.

“We did encounter a number of known checkpoints, but there was no hostilities at those checkpoints,” Oliveto said.

The convoy received additional security from a number of military elements. Among them, a special-purpose task force established by the Marines in 2013 to provide security in crises in northern Africa following the Benghazi attacks deployed two MV-22B Ospreys carrying Marines in case a quick-reaction force was needed.

Two Air Force F-16 fighter jets also stayed overhead in case bombs needed to be dropped, and the Navy supplied at least one drone to provide surveillance, the Marines said. Special Operations troops with U.s. Africa Command also provided undisclosed support.

Black smoke billows from a fuel storage depot near the airport in Tripoli on July 28 after it was hit by rocket fire. (EPA/STR)

After crossing the border into Tunisia, the convoy was escorted by the Tunisian national guard another 10 hours to an airfield, Oliveto said. The Americans were picked up by aircraft and taken across the Mediterranean to Naval Air Station Sigonella, from which Marines had been monitoring the operation. Eighty-one of the people evacuated were Marines and sailors.

DeTreux said that the Marines understood that they were the supporting the State Department on the mission, and received good cooperation from them. The colonel’s concerns were “alleviated in a very short time” once he had a better sense for the ambassador’s preferred plan, he said.

“She wanted to quietly slip the mission out, and nobody can knock the plan because it was successful,” DeTreux said.

State Department officials said in July that the embassy would be closed only temporarily, but it has not reopened and was taken over by the Dawn of Libya militia group afterward, the Associated Press reported. Moussa Abu-Zaqia told the AP that embassy personnel were welcome back with “no troubles at all” and that his militia wanted to clean up the compound after it was battered with rockets and other weapons.

Video of militia men swimming in the embassy’s pool surfaced online in August. Jones, the ambassador, said on Twitter that it appeared to be legitimate. She and her staff have been working since the Tripoli embassy’s closure from Malta, an island in the Mediterranean, officials said.