The Marines from a Marine Air-Ground Task Force based in Moron, Spain, were expected to arrive in Senegal Wednesday night and then move to Liberia. Two KC-130 aircraft from Moron were also headed to Senegal.
The Marines and the Ospreys were being deployed to fill a void in transporting medical aid and personnel to remote areas until troops from the Army's 101st Airborne Division arrive in Liberia later this month, said Rear Adm. John Kirby, the Pentagon press secretary.
The Ospreys will "help facilitate the transportation of supplies and our own troops" in the effort to contain the spread of the virus that has hit hardest in Liberia, Guinea and Sierra Leone, Kirby said.
Airlift has been a concern in the military's response to the epidemic, and the Ospreys "can go where lots of aircraft can't go," Kirby said at a Pentagon briefing.
Kirby stopped short of describing the deployment of the Marines as a change in the military's overall plan to assist the U.S. Agency for International Development and the Centers for Disease Control in combating Ebola.
The deployment was more of an effort to "get some assets into the region" swiftly as the military's response ramps up, Kirby said. The Ospreys and the Marines were not expected to be in the region "long term," Kirby said, but the decision on the length of their stay will be up to commanders on the ground.
About 350 U.S. troops had arrived in Liberia as of Tuesday in the military response announced by President Obama on Sept. 16 that the Pentagon said could involve about 4,000 troops.
The troops will operate under guidelines aimed at keeping them out of direct contact with Ebola victims. They will mainly be involved in putting up 17 treatment centers of 100 beds each, and in providing logistical support.
About 700 troops from the 101st Airborne Division led by Maj. Gen. Gary Volesky, the division's commander, were expected to arrive in Liberia in late October. Once on the ground, Volesky will take over command of the military's Ebola efforts from Maj. Gen. Darryl Williams, who will return to his command of U.S. Army Africa.
At a Pentagon briefing Tuesday, Gen. David Rodriguez, head of the U.S. Africa Command, said the military effort in West Africa was expected to last about a year and cost $750 million. In a rare visit to the Pentagon, Obama was meeting Wednesday with Rodriguez on Ebola, and also with other combatant commanders on a range of crises around the world.
As of Oct. 3, the Centers for Disease Control said there were 7,492 cases of Ebola in West Africa, and 3,439 deaths.
-- Richard Sisk can be reached at firstname.lastname@example.org