President Obama visited Canada on Thursday in his first foreign trip as head of state, meeting with Canadian Prime Minister Stephen Harper to discuss a range of complicated economic and military issues. Obama and Harper discussed possible remedies for the global economic downturn, a new initiative to fight global warming and the ongoing struggle against Taliban and al Qaeda elements in Afghanistan, the leaders said during a joint news conference. The struggling economy was at the top of the agenda, with emphasis on the controversy surrounding the “buy American” clause in the recently passed U.S