Complex sentence: Rescue planning was complicated by the uncertainty surrounding the location of the "Mayaguez" crew, it was believed that some were still on the ship, some on Koh Tang and others were on the fishing boat bound for Kampong Som.
Split into simpler sentences: Rescue planning was complicated by the uncertainty surrounding the location of the "Mayaguez" crew. It was believed that some were still on the ship, some on Koh Tang and others were on the fishing boat bound for Kampong Som.