Olga Wojtas meets the academics who are trying to get to the root of terrorism.
"The only time that I ever came near to being filled in was a case of mistaken identity," says Steve Bruce, head of Aberdeen University's sociology department.
Bruce, researching Loyalist terrorism in Northern Ireland, had been in a club with paramilitaries when he came under attack by a man claiming his brother's life was in danger because he could be identified through photographs in a new book. Bruce protested there were no photographs in his books. He had been mistaken for a local journalist.
"There's a large part of the Ulster Defence Association who will not talk to me because they don't like things I've written. But I don't think (my research) is terribly dangerous. Only in the sense that I've often sat in rooms talking to people I knew the IRA would dearly love to kill. The doorbell rings and you wonder: 'am I going to hear the clatter of machine guns?'" James Dingley, a terrorism expert at Ulster University, says: "If you're sensible, it's probably no more dangerous than researching criminology."
He advises making it clear what your role is and never passing information between terrorist groups and the security forces.
"Terrorist groups have no real interest in attacking academics. Even if you're being critical, they've got a vested interest because you're taking them seriously, you're studying them."
But Andrew Silke, a forensic psychologist at Leicester University's Scarman Centre, warns that academics researching terrorism have been threatened, kidnapped, attacked and shot.
And Mark Galeotti, director of Keele University's Russian and Eurasian organised crime research unit, believes Northern Ireland's terrorists may increasingly be in the minority.
"There were terrorist groups you were safe with. They knew they were fighting a political struggle and talking to academics was a chance to express their point of view that they weren't just thugs and criminals. But increasingly, the pattern is very, very inchoate mixtures of terrorism, insurgency and crime."
Many terrorist groups are now more likely to see academics as potential hostages, "a walking sack of dollars", Galeotti says. He says he would steer any postgraduate away from contemplating fieldwork in Chechnya, for example.
This situation is yet one more deterrence to those thinking of becoming involved in terrorism studies, an area that many believe is under-researched in the United Kingdom. However, Paul Rogers of Bradford University's department of peace studies says: "There's probably rather more work going on than might be implied, because some academics who work in this area tend not to use the term 'terrorism'."
Terrorism is a relatively young subject area, dating from about 1968, and can come under various disciplines, ranging from political science and psychology to history, law and military sciences. It lends itself to a multidisciplinary approach, arguably offputting to academics considering the requirements of the research assessment exercise.
David Carlton of Warwick University, who teaches an undergraduate course in terrorism, says: "It ends up as being everything and therefore nothing. It links into a very large number of disciplines."
There is also the perennial difficulty of one person's terrorist being another person's freedom fighter, he says, as well as the issue of whether researchers take account of state-sponsored terrorism.
Silke, who reviews trends in terrorism research, says there is a continuing shortage of academics who make this their primary area of research. In the wake of the American hijackings, he and other terrorism experts anticipate a short-term boost in interest in the field, but question how valuable the resulting work will be. A long-term interest is essential for those building contact with terrorists. Bruce describes it as "going through the layers of an onion", talking to people in the outer fringes and gradually getting introduced to senior figures.
It took him three to four years to gain senior figures' trust. The time and uncertainty involved makes gaining funding difficult.
Dingley adds that reporting sources that cannot be revealed can hamper publication. "Mainline academic journals become very snotty about academic references. They say it's not acceptable to put 'senior members of the security forces'."
Purists look down on journals that are aimed at policy-makers and security specialists as well as academics, even when these involve reputable scholars.
Galeotti, European editor of Low Intensity Conflict and Law Enforcement, says good refereeing is essential, but there may be only a tiny number of people with the necessary expertise.
Do academics acquire sensitive information about potential terrorist attacks? Unlikely, say the specialists. Many of their contacts are used to interrogation by police or security forces and are not prone to indiscretion. Moreover, their focus is on identifying the causes of terrorism and providing dispassionate accounts of the different groups.
Silke adds that, although academic research was unlikely to have predicted the US attack, it could be useful in preparing the most effective response to it.
"We know that massive military retaliation almost certainly has no effect on terrorism, and if it does, this is likely to be very short term and increase the amount of terrorism."
Another area where terrorism research can help is in identifying trends. Twenty years ago, Carlton speculated that terrorist attacks could shift from limited numbers of casualties to mass destruction.
"The question one now has to ask is whether groups in future will feel they've made much of a point if they don't kill very large numbers of people."
In the 1980s, William Gutteridge, former professor of international studies at Aston University, raised the possibility of armed guards on planes and of screening overseas students studying aviation.
"There's no lack of publications. Some of us feel fairly frustrated. We've been concerned by how little the lessons of Lockerbie have been applied, except perhaps in Britain and Germany," says Gutteridge, a former director of the Research Institute for the Study of Conflict and Terrorism, an educational charity that folded two years ago for lack of subscriptions.
Bruce adds: "Politicians very rarely pay attention to us. Our politicians aren't readily persuaded that academics know anything."