Royal Dutch Shell Plc won U.S. approval to resume oil exploration off Alaska’s Arctic coast after regulators imposed safety conditions meant to avoid the mishaps that plagued the company three years ago. Environmental groups decried the decision. The Interior Department on Monday endorsed Shell’s plan to have two rigs drill up to six exploratory wells in the Chukchi Sea, if it gets other permits needed, sets plans to control any leaks and keeps its ships at least 4 miles away from any walruses. Shell wants to resume work halted in 2012 when its main drilling rig ran aground and was lost.