Jean-Louis Bruguière was the leading French magistrate for investigating counterterrorism from 1981 to 2007.

Paris—The failure of the United States intelligence community to prevent the Christmas Day bombing attempt is not due to the failure of any individual or department but of the system itself.

The American emphasis on tough border controls with strict immigration rules and an over-reliance on information-gathering technology has failed to make the country more secure. Only shedding this defensive approach and developing a more proactive strategy that understands the evolving nature of the terror threat, while embracing information sharing and cooperation among intelligence agencies within the US and abroad, will make a difference.

No fence—including the most sophisticated—can by itself protect a country from terrorist attack. In North America, the borderlines between the US, Canada and Mexico are particularly porous. Everyone, for example, knows about the massive flow of drugs and illegal immigrants into the US from Mexico.

Given this reality, immigration law and border controls cannot be the linchpin of any relevant anti-terror strategy. Such a defensive “Maginot Line” approach is simply outdated and ineffective, especially in the face of the shifting shape of terror networks, which are now recruiting and training citizens from the West outside their countries to go back home to commit terrorist acts.

Moreover, the fact that the US doesn’t have effective national identity controls jeopardizes its ability to detect in advance entrenched sleeping cells if their members have not already been implicated in illegal activities.

The other problem of America’s counterterror strategy involves information collection through satellites, drones, wiretaps and other communications scanning by the National Security Agency and other agencies. Too much data kills operational information.

The terrorist threat today is scattered and polymorphous. It does not issue from some central command but is a mutating system that responds to any situation or event from which it might benefit. Evaluation of threats depends on a flexibility of mindset that can match this viral behavior, allowing a prompt and adapted response.

Human intelligence sources are thus usually more effective than technical ones because motives and opportunities to act are very hard to read from a distance through opaque data. Satellites or drones cannot get inside the mind of a jihadist.

The US needs a new approach with new tools and methods. First and foremost, circulation of information in real time is crucial. Often, it is the small, apparently trivial sign lost in the avalanche of data that forewarns of a coming threat. The more trained eyes there are on information, the more likely that sign is to be read. If the information provided by the father of the Nigerian charged in the Christmas Day bombing attempt had been properly shared and analyzed, the suspect would have been prevented from boarding a plane headed to the US.

In this respect, the federal system in the US often serves to impede communication. Local police forces are often reluctant to cooperate with federal agencies, and thus information collected in the field doesn’t make it to the national government officials tasked with counterterrorism. This was noted when looking back on the lead-up to the 9/11 attacks but still has not been effectively resolved.

In fact, the situation has worsened because of the massive size of the proliferating post-9/11 agencies from the Department of Homeland Security to the National Transportation Safety Board to the National Counterterrorism Center. The Office of the Director of National Intelligence seems to encounter difficulties coordinating the activities of the intelligence community as a whole, which it is tasked to do. These constraints compromise data sharing inside each agency and between agencies. They are brakes on the implementation of a pro-active strategy that can effectively foil terrorist attacks.

Al-Qaida and its associates are a global enterprise broken up into autonomous and worldwide cells that resemble a jigsaw puzzle. Each national agency, local police force or foreign intelligence agency has a piece of the puzzle. That is why the single most important task is to develop the joint capacity to put all the pieces on the same table so that all those involved in the fight against terrorism can see the whole picture. Cooperation is the cornerstone of an effective counterterrorism strategy.

In France, we have adopted the proactive strategy I have described. As a result, France has not been hit on our soil by a terrorist attack since 1996, foiling one or two attempts a year during that period.

The final piece of a revamped US strategy involves a sharper understanding of the ever-changing shape of global terrorism today.

As the Obama administration correctly grasps, the Iraq War diverted US anti-terror efforts from the real threat in Afghanistan and Pakistan. By 2002, it was clear that President Pervez Musharraf had lost control over elements of Pakistan’s military and intelligence forces. This has had direct implications for the nature of the current wave of attacks directed against the US and elsewhere, no less in Pakistan itself.

In the course of an investigation I conducted in 2003, in the case of a European jihadist sent to Pakistan, I learned that the Lashkar-E-Tayyibba (LET) group trained many foreigners in their camps in Kashmir, including citizens from France, the US and Great Britain, in order to send them back for operations in their home countries.

The French individual involved came back to France before being ordered to join a sleeping cell of LET planning an attack in Australia. The American trained in Kashmir went back to the US and joined a cell in Virginia whose planned attacks were thwarted. All of these men, we discovered, were directly supported by active members of the Pakistani military and intelligence forces, who provided them with arms, ammunition and training.

Even though the Obama administration has elevated Pakistan in its anti-terror sights, the threat it poses directly to the US is still underestimated. This nuclear-armed state might be at risk in the future if the growing activities of the Taliban and other radical Islamist movements are not staunched in time.

Equally underestimated is the worsening situation in the Maghreb and the Sahel. In order to reinforce his operational capability during the Iraqi insurgency against the US, the late Abu Musab al-Zarkawi, who headed al-Qaida in Iraq, reached out to high-ranking members of the Algerian group GSPC (“Fighting and Preaching Salafist Group”).

After Zarkawi’s death in 2006, the leadership of GSPC swore formal allegiance to al-Qaida, meeting with high-ranking members—probably Ayman al-Zawahiri—in the tribal zones of Pakistan and changing its name to “Al-Qaida in the Maghreb Lands” (AQIM).

As part of the al-Qaida network, the aim of AQIM is to destabilize the Maghreb, mainly Algeria, and extend its activity into the Sahara using Mali, a very weak country, to set up a stronghold in Mauritania. From this country, AQIM plans to extend its influence to West Africa. It is now recruiting members in Senegal and has established operational connections with cells in Niger, some of which are suspected of links with radical Islamists in Nigeria, the home, of course, of Umar Farouk Abdulmutallab, the man charged in the Christmas Day bombing attempt. More than a mere coincidence, this is a visible sign of the increasing role of Africa as a breeding ground for terrorism.

Clearly, the failed Christmas Day terrorist act has jolted the US into a recognition that attacks on its homeland will be a part of al-Qaida’s strategy for a long time to come. The best way for the US to defend itself is to go on the offensive with a pro-active strategy that beats al-Qaida and its allies at their own game.