SALT LAKE CITY -- The show behind the scenes was just as impressive as the one planned inside. Before one athlete entered the Olympic stadium Friday night, the greatest defense in the history of sport was already well under way.
With snipers on the rooftop and Black Hawk helicopters hovering overhead, a massive $310 million effort to protect the Olympics moved into full gear after nearly three years of planning.
Unlike the performers in the Olympic opening ceremony, though, the thousands of agents, police and military couldn't afford to make even the most minor mistake.
"We don't get a second chance," Secret Service agent Mark Camillo said.
Although no credible threat has surfaced against these games, top administration officials have warned that the Olympics could be a prime target of terrorists.
Security agents took no chance in a complex plan that includes 59 agencies and employs nearly 16,000 security workers on everything from snowshoes to fighter jets.
It began for real Friday with a ban on all air travel in and out of the city's airport during a three-hour opening ceremony that was to include President Bush and U.N. Secretary-General Kofi Annan.
The security force was busy around the stadium in the hours before the ceremony, and a maze of fences and checkpoints stretched up to a half mile from its perimeter.
Police patrolled the fences on all-terrain vehicles, while helicopters kept watch overhead. The adjacent University of Utah campus, usually bustling with activity, was nearly deserted.
"All that can humanly be done to make this a safe place will be done," Utah Gov. Mike Leavitt said. "This will be a safe place."
Most of the 2,500 athletes didn't need to be convinced. Although polls showed Americans worried that terrorists might attack the games, all the security checks, police and National Guardsmen patrolling the area made them feel more secure.
"It's like when I crawl in bed at night and I have my down comforter," said Nina Kemppel, a cross-country skier and four-time Olympian. "It's that same kind of comfortable, fuzzy feeling."
The suffocating security meant spectators had to leave for events hours in advance. Even then, they were likely to spend a lot of time waiting in line in the cold to be searched before entering the stadium for the ceremony. Afterward, more lines were expected for public transportation home.
With more than 50,000 fans expected at the opening ceremony in the first major test for Olympic security, getting through metal detectors was expected to be a chore. During rehearsals, one out of every two people set off the detectors and had to be searched, leading to waits of up to 90 minutes in line.
Earlier Friday, there were long lines to get into the downtown medals plaza, where the only thing to see was an Olympic souvenir store and a few exhibits.
A security guard shouted at people to open their bags and remove anything from their pockets that could set off metal detectors. The line stretched across a parking lot and into the street.
At the nearby Salt Lake Ice Center, where figure skating will be held, strong overnight winds delayed the arrival of additional metal detectors, and there were long waits to get into practice sessions.
At the airport, flights were rerouted as authorities moved to enforce a shutdown of flights during the opening ceremony. Some 320 flights were rescheduled or canceled during a four-hour period from 6-10 p.m.
Flight restrictions went into effect at midnight Thursday for a 90-mile wide area over Salt Lake City for the remainder of the Olympics. Until the games are over, only commercial airliners and planes that go through security checks at four gateway airports in other states will be allowed through the airspace.
Making sure the airspace is clear will be about a dozen U.S. Customs Black Hawk helicopters and several F-16 jets stationed at nearby Hill Air Force Base.
"If you violate the restrictions you will be able to tell your children and grandchildren you flew formation with the Department of Defense or Treasury Department," FAA spokesman Mike Fergus said.
Even the most mundane matters got some attention. Australia's security director warned his country's athletes against buying Valentine's Day flowers outside the Olympic Village because they could be sprayed with anthrax.
"We're just being cautious," Bob Myers said. "I guess you could say over cautious."