Cadillac strategy chief suddenly steps down, GM says DETROIT (Reuters) - Don Butler, the head of global strategy for General Motors Co's luxury (GM.N) Cadillac brand, resigned on Monday about four months after he was assigned to boost the nameplate's international sales. Butler made the decision to leave for personal reasons after "three years of pouring everything into Cadillac," GM spokesman David Caldwell said. He wanted to step back, spend more time with his family, consider new avenues. The decision came as a surprise and Butler was asked to stay on at GM, where he is an "extraordinarily well-liked guy," Caldwell said. He said the company was looking for Butler's replacement but offered no time table. In April, Butler was named to the newly created role of vice president for global Cadillac strategic development. He reported to Bob Ferguson, GM's global Cadillac chief. GM's drive to make Cadillac a global brand took shape after the company's 2009 bankruptcy restructuring. In June, the No. 1 U.S. automaker unveiled plans to expand its retail network in China, the world's largest car market. Automotive News first reported Butler's resignation. Reporting by Deepa Seetharaman; Editing by Leslie Gevirtz