IT is little comfort to the families of those murdered but the evidence is that the life cycle of a terrorist group is 40 years and of many much less, and very rarely goes into a second generation. Policymakers and the media skim over the built-in weaknesses of terrorist groups. The highlighting of their dastardly deeds gets full play, but the potent evidence that points to infighting and fractionalizing is downplayed. The opening of recent archives shows that even heads of government including the president of the US have not been given the raw material on this by their intelligence services to make up their own mind.

Members of the West German Second of July Movement (an ally of the Baader-Meinhof group that caused mayhem in the 1970s) shot a colleague because they believed he had botched a bombing and become a police informant. A few weeks later, a member was murdered because he had refused to murder a colleague. Similarly, Le Front de Liberation du Quebec self-destructed because of bitter internal disputes. In 1969, 14 members of the Japanese Red Army were tortured and killed by their compatriots because they disagreed over ideological issues. Competing terrorists jockey with each other for position as between Palestine groups in the second intifada, strengthening the upper hand of the Israelis.

Terrorists often overreach, losing what civilian sympathy they may have built their strength on. Al-Qaeda is the best example. Its support is a poor shadow of what it had at the time of 9/11. Finding support for it in the Muslim world today is almost akin to finding a needle in a haystack. The splinter group of the IRA, the Real Irish Republican Army, never recovered its standing after the Omagh bombing that killed women and children after the Good Friday truce. When in 1978 the Italian Red Brigades murdered the former prime minister, Aldo Moro, that was their end as far as public opinion was concerned. Soon after, all their leaders were rounded up. But public opinion is fickle, ill informed and easily manipulated by the authorities and the press and, among young people, too often subject to the romanticizing of would-be revolutionaries. Che Guevara remains even today an icon in tens of thousands of student-frequented coffee shops all over the world.

By hiding with a few dozen followers in Afghanistan, Osama Bin Laden brought the wrath of the Western war machine onto a people who, despite their warrior reputation, are essentially peace loving and politically quiescent. This has done more than Al-Qaeda could ever have done on its own to give the movement life — all at the expense of mainly innocent people. Now the main unspoken reason for continuing fighting in Afghanistan is to preserve the esprit de corps of the Western militaries. The shadow of the Vietnam defeat is a long one.

In time Al-Qaeda is likely to destroy itself by its own internal feuds, admittedly only under pressure. But that must be implemented not by armies and inaccurate drones but by tough policing. The many Al-Qaeda-type cells in Europe, Canada and the US have been broken by solid police work.

At the heart of Al-Qaeda is a belief in a single strand of Islamic teaching. According to “How Terrorism Ends” by Audrey Kurth Cronin, “One long-standing source of dispute is the argument between those who adhere to the beliefs of revered Hadith scholar, Shaik Al-Albani, who argues that jihad should entail elements of compromise and those who, like Ayman Al-Zawahiri, Bin Laden’s deputy, who argue that anything less than killing the infidels is “appeasement”. Likewise, a divisive and passionate element of discord is the issue of whether or not it is acceptable to kill Muslims, particularly the elderly, children and women.

In Iraq the cruelty of the Al-Qaeda affiliate with its assassinations, enforced suicide bombings, beheadings and forced marriages repelled Iraqi Sunnis. Al-Zawahiri wrote a letter to Abu-Musab Al-Zarqawi, the local leader, asking him to desist.

Good police work, a la the Israeli effort to capture Adolph Eichmann, is the way to go with Bin Laden and his merry men. Anything else contains the seeds of its own failure.