Individual units did not learn about their planned participation until 17 January. The Airborne Division that was to lead the operation received no detailed plans until 2 February, less than a week before the campaign was to begin. This was of crucial importance, since many of the units, particularly the Airborne and the Marines, had worked as separate battalions and brigades and had no experience maneuvering or cooperating in adjoining areas. According to the assistant commander of the U.S. 101st Airborne Division, "Planning was rushed, handicapped by security restrictions, and conducted separately and in isolation by the Vietnamese and the Americans."