SAN FRANCISCO  The Olympic torch arrived at the airport here from Paris in the wee hours Tuesday morning, exited out a side door and was escorted by motorcade to a downtown hotel. There it took a well-deserved break in a room complete with cable TV, room service and views of the city’s popular Union Square shopping district.

“It has very comfortable accommodations,” said Mike McCarron, an airport spokesman, who said the flame  ensconced in a handsome brass lantern and accompanied by several backup flames  was “treated similar to a head of state.”

On Wednesday afternoon, the flame will be under no such bushel as it makes its only appearance in the United States on an increasingly tense international tour en route to Beijing. It will star in a two-and-a-half-hour relay along this city’s waterfront, involving six miles of pavement, 79 runners and untold scores of law enforcement officials.

The precise route remained in flux on Tuesday as the torch extravaganza threatened to become more civic migraine than celebration in the face of potential protests by those upset with China’s human rights record and recent crackdown in Tibet. Mayor Gavin Newsom met with police and relay officials amid concerns that disruptions in London and Paris this week not be repeated here.