sigma ii was held by the joint chiefs of staff in september the game results predicted that so long as the communists maintained the guerrilla tactic of picking when they wished to fight and they had safe haven over the borders of cambodia and laos they would not suffer sufficient casualties to end the war both bombing campaigns then in progress rolling thunder and barrel roll were deemed to have limited effect on communist operations general william westmoreland's strategy as expressed in his september mission statement was based on attrition the sigma ii results contradicted that as a result secretary of defense robert s macnamara began to doubt westmoreland's expertise addington p sigma ii