A group of Royal Marines based near Taunton are heading to a training exercise in the Mediterranean three weeks earlier than planned.
Three companies from 40 Commando left for Suez on Tuesday. They will take part in sea exercises with Nato forces.
Commanding officer Lt Col Matt Jackson said they were not going to fight in Libya but were being moved to the area for possible humanitarian support.
The Ministry of Defence said Operation Cougar had been two years in planning.
The United Nations resolution on Libya forbids troops on the ground other than to help with humanitarian aid.
The marines returned from a six-month tour of Afghanistan in October.
Joyce Parsons, who attended memorial services at a church in Norton Fitzwarren to honour marines who had been killed, said she was not happy with the latest deployment.
"The young men have just got back to living with their families. I find it sad they're taken away so quickly," she said.