The protective postures are also used in the event a ship passes through a chemical cloud or is exposed to fallout etc…. All operations are conducted under the MOPP system, even when there is no threat. There are four levels of MOPP—from Level-1, the least protection, to Level-4, the most protection. MOPP 1. All ships are at this at all times. General Condition of Readiness. MOPP Level-1 1.