In the 1950s British trawlers fished for cod off Iceland, provoking Iceland to increase its maritime boundary from 3 nautical miles offshore, first to 4 and eventually up to 200. British fishers largely ignored these new boundaries. Iceland equipped its coast guard with cutters to slice the nets off unwelcome trawlers. Britain responded by ramming Iceland’s ships. The Cod Wars continued until the 1970s, when Iceland threatened to withdraw from NATO.