Warplanes patrolled American skies and international airlines placed sky marshals on some flights Wednesday as fears of a terrorist attack cast a giant shadow over New Year’s celebrations across the globe. Millions of New Year revelers were expected to throng city centers across the world Wednesday under a security umbrella raised amid fears of a terrorist attack, possibly involving aircraft. Some international airlines, responding to a U.S. warning of a possible attack by Islamist militants, placed armed sky marshals on flights. Cities from Rome to New York imposed flight restrictions and airports stepped up security. Full Story