WATERTOWN, S.D. - (AP) Barack Obama laid into John McCain on Friday for advancing a tough-guy foreign policy that he called "naive and irresponsible," serving notice that he's ready to launch a full-throttle challenge to the Republican presidential contender on international relations in the general election campaign. Lumping McCain together with President Bush, Obama declared: "If they want a debate about protecting the United States of America, that's a debate I'm ready to win because George Bush and John McCain have a lot to answer for." He blamed Bush for policies that enhance the strength of terrorist groups such as...