Security was tightened across the nation yesterday as authorities towed vehicles parked in front of New York churches and synagogues, South Carolina probation officers were assigned to guard nuclear plants, and scuba divers inspected the hulls of ships berthing at Los Angeles harbor. As Americans braced for war with Iraq, the Department of Homeland Security implemented a temporary policy of detaining asylum seekers from 33 nations where al Qaeda is known to have operated, an action that could result in hundreds of arrests. With the nation’s terrorist threat level at orange, indicating “high risk,” New York City police established extra checkpoints at bridges and tunnels — where officers inspected driver’s licenses — and patrolled newspaper and television network headquarters to discourage terrorist attacks. Full Story