VANCOUVER - Sending two fighter jets to escort a Vancouver-bound airliner as passengers watched them unaware there had been a bomb threat was an "appropriately cautious" response, a terrorism expert said Sunday.

The pair of CF18 Hornet jets intercepted the Cathay Pacific plane, carrying 283 passengers and 14 crew members on a flight from Hong Kong, on Saturday. A subsequent search of the plane turned up nothing.

Still, Stuart Farson, who teaches at Simon Fraser University, said NORAD's reaction to the threat should come as no surprise in a world of tightened security following the Sept. 11, 2001, terror attacks in the United States.

"Since 9-11, this has been part of the program," Farson said in an interview.

"I think it's just being appropriately cautious. The guys at NORAD just don't have the time to identify what the threat actually is. You have to take some sort of action."

The RCMP said it received a threat shortly before 11 a.m. local time on Saturday morning, almost three hours before the flight touched down in Vancouver.

The North American Aerospace Defence Command, or NORAD, responded by sending two fighters from a Canadian Forces airbase in Comox, B.C., that stayed with the plane until it landed.

The Mounties have said very little about the nature of the threat, except that, in the end, "there was no threat aboard the aircraft." A spokesperson for the force said Sunday they were looking for the person who made the bomb threat.

The passengers weren't told what was happening as two military jets suddenly appeared alongside the plane in the air.

Farson said that wouldn't have done any good.

"What do you tell the passengers — 'We've got a bomb on board'?" said Farson. "That's going to cause panic, and I think you want to avoid that in all cases."

A similar incident happened in 2004, when an Air Canada Boeing 767 flying to Vancouver from Toronto received a military escort after the RCMP received a threat.

At the time, the RCMP said a subsequent investigation concluded there was no real threat.

A spokeswoman for NORAD said the Canada-U.S. military alliance dispatches aircraft to about 200 incidents in North American airspace each year, including threats such as what happened with the Cathay Pacific flight, disturbances on planes, and enforcing flight restrictions.

Maj. Holly Apostoliuk said NORAD officials don't have time to verify a threat is genuine before responding.

"Considering the time available when information is receive about a potential threat to an aircraft, one does not have time for a full investigation, and neither would anyone want us to do so," Apostoliuk told The Canadian Press.

"The point is, based on the information, to do all we can to ensure a safe landing of the aircraft."

The airline couldn't be reached for comment Sunday, although a statement released on Saturday praised the military and police response.

"It is very heartening to know that Canada — and Vancouver in particular — is so well prepared to handle a real crisis should one occur in the future," the company said.