WASHINGTON ― So next time the Norwegians will arm more of their police. And next time, authorities will investigate the ranting manifestos of any anti-Muslim extremist who claims to lead a revival of the medieval Knights Templar. 

But the July 22 attack in Oslo by Anders Behring Breivik teaches some broader lessons too: There are homicidal cults all over the world ― some in Muslim countries and some in the heart of Europe. Some attackers will be found insane by courts but others will have a diabolical logic and lucidity ― and the world has to be ready for all of them.

Most important, the next time the weapons of choice may not be a bomb and a semiautomatic rifle, as in the case of the Oslo attacker who killed 76 people. Lunatics and sane plotters alike may have access to chemical and biological weapons that could kill thousands.

As in so many terrorist cases ― and with al-Qaida itself ― this latest extremist didn’t sneak up on the world in secret. He all but announced his anti-immigrant views on the Internet.

To understand the dangers posed by these borderline extremists, I recommend a new report by Richard Danzig and his colleagues at the Center for a New American Security. It’s a case study of the only terrorist group that has successfully used chemical and biological weapons on a mass scale ― the Japanese religious cult Aum Shinrikyo. It poisoned the Tokyo subway system with sarin, a deadly nerve gas, in 1995, causing 13 deaths and an astounding 6,252 injuries.

Danzig’s report, drawn from interviews over the last three years with imprisoned members of the cult, is revelatory. It shows how extremists are driven toward ever-more toxic weapons. And it illustrates how lax police can be until disaster happens. Though the Japanese police had evidence that Aum Shinrikyo was producing chemical weapons, they couldn’t prosecute because no Japanese law specifically banned manufacture of poison gas!

The report makes some interesting contrarian points, too. There’s a self-limiting quality in these terrorist cults ― an emphasis on secrecy and hierarchy that sometimes prevents them from using materials they can so easily obtain. They botch repeated attempts to make their weapons work. But they are persistent: They keep coming back, until they get it right.

This finding surely fits al-Qaida, the masters of trial and error. And it applies to other groups, whose names we won’t know until they burst out in bloody headlines, as with Breivik and his vision of the Knights Templar.

The Aum Shinrikyo story centers on a bearded, nearly-blind Japanese cult leader who called himself Shoko Asahara. In the beginning, the group was a peaceful proponent of yoga and a purifying “original Buddhism,” but it soon took on a political mission. Asahara tortured his wife until she complied with his vision, and he began experimenting with botulism toxin in 1989 to kill a renegade member of the order.

A common strand with Asahara, the Norwegian Breivik and al-Qaida’s Osama Bin Laden is that they all embraced grandiose schemes for imposing their political-religious order of things. Asahara literally drew his inspiration from science fiction ― imagining plasma ray guns that could vaporize humans, and floating mirrors in space that could zap earthlings.

Aum Shinrikyo tried and failed repeatedly on its way to the successful 1995 subway attack. Its first big batch of nine tons of botulism toxin was so useless that when a cult member fell into the vat by accident, he was unharmed. A test effort to kill 2,000 mice failed. A plan to spray anthrax failed because of a faulty sprayer, as did an attempt to blow anthrax powder. The group tried to use VX nerve gas a half-dozen times in assassination attempts, and failed each time.

Yet they kept on coming, finally with the nerve gas sarin. The first attack was a 1994 attempt to kill judges opposing Aum Shinrikyo in a commercial case, but the nerve gas blew instead into an apartment complex, killing eight and injuring 200. The next year came the horrific Tokyo subway attack ― all but advertised in advance and still unstopped.

Danzig and his co-authors make the essential point: In dealing with these extremist groups and cults, the world is playing Russian roulette: “Many chambers in the gun prove to be harmless, but some chambers are loaded.” Another bullet was fired last Friday, and we are surely clicking toward more. The surprise is that we’re still surprised. 

By David Ignatius

David Ignatius’ email address is davidignatius@washpost.com ― Ed.

(Washington Post Writers Group)