 Some have accused the early Fordist model of production of being exploitative, and Ford has been criticized as being willing to collaborate with dictatorships or hire mobs to intimidate union leaders and increase their profits through unethical means.Ford refused to allow collective bargaining until 1941, with the Ford Service Department being set up as an internal security, intimidation, and espionage unit within the company, and quickly gained a reputation of using violence against union organizers and sympathizers.Ford was also criticized for tread separation and tire disintegration of many Firestone tires installed on Ford Explorers, Mercury Mountaineers, and Mazda Navajos, which caused many crashes during the late 1990s and early 2000s (decade).