Maritime Security Operations (MSO) is a term for the actions of modern naval forces to "combat sea–based terrorism and other illegal activities, such as hijacking, piracy, and slavery, also known as human trafficking."[1] Ships assigned to such operations may also assist seafaring vessels in distress. These activities are part of an overall category of activities which fall short of open warfare called military operations other than war (MOOTW).
An example of such operations is the involvement of the multinational coalition Combined Task Force 150, which performs Maritime Security Operations in the Indian Ocean and Persian Gulf. During the Somali Civil War, they provided anti-piracy operations along the coast of Somalia in international waters. During the 2006—2007 war, they performed a cordon along the coast to prevent the escape of Al-Qaeda operatives by sea.
A primary component of MSO requires inspections and, at times, forced boardings of vessels at sea. These actions are called Visit, Board, Search, and Seizure (VBSS).