By DOUGLAS MURRAY

London

It is almost two years since terrorists from Lashkar-e-Taiba traveled to Mumbai, India, and carried out a string of attacks on hotels, cafes, a Jewish center and other civilian targets. The horrific footage of those attacks spread around the world and raised obvious questions: Would it happen again—and if so, where?

In the past week that question appears to have been answered. Increasingly credible reports have emerged claiming that Predator drone attacks in Pakistan have killed a number of people planning Mumbai-style attacks in Western European cities. This fits with the increased number of alerts and heightened threat levels across Europe in recent weeks. Last weekend the British Foreign Office changed its threat level to “high” from “general.”

And there is another element of the story that suggests its authenticity: Two British citizens are among those reportedly killed in the Pakistan drone strikes, along with several German nationals.

Lashkar-e-Taiba certainly has links to the United Kingdom, the Western center of jihad. A comprehensive report published in July by the Centre for Social Cohesion, “Islamist Terrorism: the British Connections,” revealed that 5% of the Islamists convicted of terrorism-related offenses in Britain over the past 10 years have links to the group. What is striking is the ambition of the plots they have been involved with.

Shehzad Tanweer, one of the suicide bombers who attacked the London transport system in July 2005, was associated with Lashkar-e-Taiba. So were British-born Omar Sheikh, convicted in a Pakistani court for his role in the killing Wall Street Journal reporter Daniel Pearl, and Rashid Rauf, the suspected ringleader of the 2006 trans-Atlantic airline plot (himself reportedly killed in a missile strike in Pakistan two years ago).

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AFP/Getty ImagesA Mumbai-style attack in the West is all too easy to imagine.

A further five men with links to Lashkar-e-Taiba have been convicted of terrorism-related crimes in the U.K. They include Dhiren Barot, the head of a U.K.-based terror cell that planned a series of attacks against major targets including financial buildings, and Omar Khyam, convicted in 2007 for heading a cell that aimed to use fertilizer bombs to attack targets including a shopping center in Kent and a nightclub in London.

It is also significant that once again the source of this latest plan appears to have been Pakistan. In 2008, then-Prime Minister Gordon Brown said three-quarters of the serious terror plots being aimed at Britain originated in Pakistan. The head of MI5 said last month that this figure now stands at 50%, but this reflects the troubling rise in activity in Somalia and Yemen, not a decreased threat from Pakistan.

Pakistan’s ability to export security problems around the world—as the Times Square car bomb reminded us—continues to grow. The man who placed that bomb set the timing device at “7:00,” but it was a 24-hour timer that should have been set at 19:00 hours (which was when he wanted it to blow). Only that mistake stopped the killing and wounding of countless people.

The United States has, like the U.K. and Europe, been exceptionally lucky in avoiding recent attacks. But the paucity of recent attacks on Western cities has also been the product of exceptional work by our intelligence and security agencies. As events in Pakistan remind us, our forces have repeatedly proved highly capable at infiltrating and eavesdropping, often allowing them to kill the terrorists before they can kill us. This is good and important work. But it must not make us think that we can always be entirely free from risk.

Announcements from American and British authorities are of questionable usefulness. Telling tourists in Europe to be wary of public places may actually play into the terrorist game plan better than anything else. What are such tourists meant to do? Stay in their hotels? Not travel in the first place?

Islamist groups aspire to carry out attacks like those in Mumbai precisely in order to trigger such fear. Civilian targets are attractive to terrorists because they are weak targets, with generally poor security unable to fight off attackers armed (like those in Mumbai) with rifles and grenades.

But there is another reason that weak civilian targets constitute such an attraction: They produce terror in its purest form. Even leaving aside any devastation caused by the attacks themselves, any Mumbai-style assault in a city such as Paris or London could have an effect on the way in which the public approaches day-to-day life.

In 1996, the Provisional IRA exploded a bomb in the heart of Canary Wharf, London’s financial district. The explosion killed two people and wounded dozens, but the financial cost came to an estimated $135 million. It requires very little money to pack a truck full of fertilizer and place it in a civilian area. And as the IRA famously said after attempting to wipe out the British cabinet in 1984, the terrorists only have to be lucky once, while we have to be lucky all the time.

One of the most common taunts of Islamists is, “We love death more than you love life.” At some point they will find another opportunity to demonstrate this. In the meantime, if death is so attractive, then we should do what we can to bring it to them.

Mr. Murray is director of the London-based Centre for Social Cohesion.