WASHINGTON (CBSDC/AP) — In the fight against violent extremism, President Barack Obama argues the U.S. has one thing going for it that Europe doesn’t: a long tradition of warmly embracing its immigrants, including Muslims. With the Islamic State of Iraq and Syria spreading and terrorists gaining strength in the Mideast and Africa, Obama has sought to use this week’s White House summit on violent extremism to urge the world to broaden its response far beyond military interventions. U.S. airstrikes have managed to blunt some of the militants’ gains in Iraq and Syria, but they don’t address the extreme ideologies that...