Responding to warnings of possible terrorist strikes once war begins in the Persian Gulf, Salt Lake International Airport, utilities, oil companies and law enforcement agencies have stepped up security.

The Federal Aviation Administration ordered Salt Lake International to tighten security before Tuesday's midnight deadline expired, allowing troops to oust Iraq from Kuwait by force.But neither the airport nor the FAA would say when or why the security alert was given. The FAA regional office in Seattle would only release a one-sentence prepared statement: "The FAA is working closely with the airlines and airport authorities to ensure a heightened level of security for the traveling public."

Airport director Louis Miller said security has been increased from level one to level two. He declined to elaborate on the difference between the two levels, saying that was classified information.

But he did say the difference isn't noticeable. "It's basically just a heightened awareness."

Every airport has a five-level security plan, with normal security being level one and security becoming tighter at each level. The plans differ based on an airport's layout, military use, general aviation use and international traffic, Miller said.

"I wouldn't want to speculate what the security level would be if war broke out," Miller said.

Other facilities and law enforcement agencies around the state also declined to give details of security plans for fear of giving would-be terrorists or even pranksters any ideas. But they all said they were aware of the potential for trouble and they have intensified security.

"We're putting on extra manpower should something happen," said a Public Safety officer, referring to security at the State Capitol while the Legislature is in session.

Hill Air Force Base is also on alert to watch for terrorist activities. "We have increased security awareness and will take whatever measures we feel appropriate to the situation," spokesman Len Berry said.

According to national news reports, public utilities such as electrical power systems, telephone lines and drinking water plants could also be terrorist targets.

"Under normal security it would be very difficult to damage the phone system. But we are strengthening measures (placing guards) at key buildings with switching systems and customer records," said US WEST Communications spokesman Gary Spendlove.

Other steps the phone company is taking include, checking packages brought into buildings, advising employees to wear their name identification tags and alerting security of those who don't.

Aware of their vulnerability to sabotage, local water districts have asked employees to watch for unusual activity near treatment plants and to take extra care in locking gates and doors.

Managers said water is tested daily for contamination, although the plants are limited in what they can detect. "We are kind of edgy here," said Salt Lake County Water Conservancy District manager David Ovard.

North Salt Lake oil refineries have also taken steps to avoid damage to pipelines and other facilities. "We have additional security measures taking place," said Randall Couch, Salt Lake manager for Amoco, which owns a pipeline from Fort Laramie, Wyo., to Salt Lake City.

"It's in everybody's best interest to keep the refinery secure. It's a safe place, but it's a hazardous place too," said Chevron refinery manager Lance Gyorfi.

An area where people always react to public issues is the University of Utah campus, where safety personnel have been keeping a close eye events there.

"We are ready to act, but we are not going to overreact. It's a matter of watching and monitoring. And threats will be taken seriously," said campus police chief Wayne Shepherd.

He said his forces have more experience with bomb threats than other local agencies. In addition, the university can call on military explosives experts at the nearby Fort Douglas, Shepherd said.