The thousands of terrorist bombings, hijackings and other incidents now afflicting the world every year have spawned a lucrative industry for American businessmen peddling counterterrorism tactics and technology.

Of 3,525 major terrorist actions counted worldwide in 1984 by Risks International Inc. of Alexandria, only 10 occurred in the United States. But there has been explosive growth among U.S. companies selling barrier systems, closed-circuit television cameras, entry control devices, armored cars and assorted other security gadgets abroad, as well as among the consultants, contractors, training centers and analyzers who put it together.

The trend is upward. "When the economy is good, people can afford to pay attention to security, and when it's bad they must pay attention," said Terry F. Jacobsen, president of Sierra-Sin Transtech Inc., which makes bulletproof glass. "With the world terror situation the way it is, it's good for business, but it's bad for my family, of course."

The U.S. government, already a major purchaser of antiterrorism expertise, last month asked Congress to authorize a $4.2 billion, decade-long program of antiterrorism construction, training, organization and electronics security equipment for more than 300 U.S. facilities overseas.

State Department officials estimated that at least 75 percent of that will go to U.S. contractors, manufacturers and transporters.

Architects now advertise that they specialize in security; closed-circuit cameras can come with explosion-proof casings; robots can handle bombs; doors resist bullets and battering for 15 minutes, time enough for diplomats to burn sensitive documents.

The General Services Administration's Interagency Committee on Security Equipment holds a symposium twice a year to tell the industry what its needs are. Five years ago, Jacobsen said, the U.S. embassy market for security glass "didn't even exist."

Ten years ago, retired high-tech electronics specialist Harry D. Dickenson and his daughter were working in their Burbank, Calif., garage making automatic ticket dispensers for parking lots, calling themselves Delta Scientific. Then they built a spiked grate to help lot owners deter nonpaying departures, then bigger systems for hotels and airports, and then barricades.

This year Delta expects to sell $10 million in Dickenson's patented hydraulic rotating barrier systems, steel wedges that lie flat in a driveway but can roll up in one second to confront oncoming vehicles with a convex steel wall up to 38 inches high. There are eight around the U.S. Supreme Court; the U.S. Embassy in Rome has two different types; the Islamic Convention Center in Kuwait will have one this year.

"We look to growth of 35 to 40 percent per year just relating to the terrorist end," Dickenson said. Many firms cite similar figures, although they are often small companies of the sort that spring up around any lucrative trend and disappear a few years later.

The Hess & Eisenhardt Armoring Co. of Cincinnati, the nation's oldest and biggest "discreetly armored passenger vehicle company," sold 90 percent of the 400 cars it produced last year overseas, according to sales vice president Thomas J. Burke. He said half of those were "full-treatment armored," able -- at a cost of $200,000 to $1 million each -- to protect passengers from grenades, bombs, automatic weapons fire "and just about any kind of assault" while looking like a luxury limousine.

Buyers may choose among 90 options, including blinding lights, firefighting systems, smoke bomb or tear-gas ejectors and devices that scatter hundreds of marbles under any nearby feet.

They may also have their own cars armored for about $100,000. Business has been so brisk that orders made today will be delivered in six months, three months longer than usual.

"Security is a custom business that doesn't lend itself to mass production," Burke said. In Italy, for example, where streets are narrow and cars are small, customers order armored Peugeots, Opels and the like instead of Cadillacs in keeping with the newest rule of this deadly game: to avoid attack, lower your visibility.

Counselors are making money selling such advice. "The companies selling widgets make good press, but I've been more impressed by the growth of programmatic things," said William C. Cunningham, co-author with Todd H. Taylor of the Hallcrest Systems Inc. report called "Private Security and Police in America."

He said dozens of consultants and security system engineering firms now advise executives on how to minimize their offices' vulnerability to attack, reduce their chances of being kidnaped and install the right security equipment. Risks International, 8 years old, has files on 22,000 terrorist incidents dating to 1970 and puts out weekly, monthly and quarterly analyses for more than 100 clients.

"We don't do anything a corporation couldn't do except for the time and energy it takes to do it," president Eugene Mastrangelo said.

As in any new field, there are sometimes abuses.

"We've got so many experts on terrorism it's nauseating," said Warren H. Metzner, past chairman of the terrorist activity committee of the American Society for Industrial Security, a professional association of 23,000 corporate and government security officials based in McLean. "This is probably one of the most marketable commodities anybody's come up with in years. Hang the word terrorism on it and it's amazing how it causes people to respond."

He recalled one firm that made an armored box to install inside a conventional automobile without protecting the tires and gas tank area. Other experts noted that barriers may not be the right defense for a transport company with a lot of traffic and that, with no formal standards to meet, anyone can hang out a consultant's shingle.

"It might be shocking to go around and see how much is serving the purchaser ineffectively," Metzner said.

Metzner's successor on the committee, Myron Weinstein, said the vast majority of corporations employ security officials whose jobs include thinking about possible terrorist threats. "It's like doctors all deal with AIDS acquired immune deficiency syndrome now; it's a topic in every board room," he said.

Claude Watkins, of Reston, spent 18 years training Air Force pilots on how to avoid capture and how to behave as prisoners of war. Now retired, he works part time giving three-hour seminars on travel security and hostage survival for about $500 a class. "I don't know another soul in the business. It's word of mouth; people just come to me," he said. Watkins is booked into April.

The Hallcrest report put the U.S. private security industry at $22 billion in 1981, with an annual 12 to 15 percent growth rate, compared to $14 billion for all the tax-paid police, deputies, troopers and federal security organizations in the country. But experts agreed that the antiterrorism share of those figures is impossible to determine because nearly all the devices and services function primarily to halt ordinary crime: breaking and entering, employe theft and industrial espionage.

Bodyguards, for example, can find work keeping friendly crowds from kissing rock stars as well as keeping terrorists from shooting diplomats.

Richard W. Kobetz & Associates Ltd., a Berryville, Va., executive training school, has 200 applications for each of three courses Kobetz offers every year to 30 aspiring bodyguards. "It's the same techniques whether it's an attack in a parking lot or stopping three armed gunmen on the premises," he said.

The course costs $2,100, and 75 percent of the takers once worked with law enforcement agencies. Now 70 percent are from private corporations, Kobetz said, and business last year was almost $5 million.

The shift may be in part because of what Yonah Alexander, editor of the quarterly journal, Terrorism, called a roughly stable cycle of terrorist activity.

Attacks of the late 1960s and early 1970s focused on diplomats and military officials, but turned to businesses in the late 1970s when embassies and garrisons began to fortify. Then businesses upgraded their security, so in the 1980s terrorists have returned to official targets with new hardware of their own.

"Now Congress is acting there and so businesses will be attacked again," said Alexander, who directs the State University of New York Institute for Studies in International Terrorism.

There is consensus that government facilities and corporations in the United States inevitably will become targets and that the security industry will boom as a result. "Spending is increasing enormously now and will continue to increase," said Rand Corp. terrorism expert Brian M. Jenkins. "There's no way around it.