President Obama on Friday stressed that the United States is not at war with Islam, blasting a Florida pastor who's threatening to burn copies of the Koran for potentially endangering American forces serving in Muslim lands. "You don't play games" with the lives of U.S. troops, an animated Mr. Obama said. In his first formal press conference since May, the president also fiercely defended a New York imam's decision to build a mosque and Islamic community center two blocks from ground zero in New York City, where nine years ago Saturday nearly 3,000 people were killed when planes hijacked by...