Homeland Security Secretary Tom Ridge is reminding Americans to remain vigilant against possible terror threats this Fourth of July holiday weekend.
The threat level remains at midpoint yellow, with no specific threat of an attack timed to the holiday.
But Ridge told NBC's "Today" show that it's "not a bad idea" to remind holiday travelers to keep a watchful eye. He says it's not necessary to raise the threat level to deploy people and technology to make Americans more secure.
The FBI is urging law enforcement agencies to step up patrols and watch for signs of terrorist activity. That includes surveillance of potential targets.
The FBI also has advice on how to spot possible suicide bombers. Tipoffs include being dressed in irregular, loose-fitting clothing not appropriate for warm weather, sweating, mumbling and refusing to show hands.