Afghanistan's defense minister, who played a key role overseeing the rapid expansion of the country's army, stepped down on Tuesday days after receiving a no-confidence vote from parliament, AP reported. The resignation of Abdul Rahim Wardak, one of the members of President Hamid Karzai's cabinet, leaves his key ministry without its longstanding leader at a time when Afghan troops are charged with taking over responsibility from international forces by the end of 2014.