Living very close to the French embassy in Washington, D.C., for many years, I often see happy crowds of people waiting in front to attend a cultural event. But on Saturday, for the second time this year, I saw tears in people’s eyes as they stood before a makeshift memorial made up of scattered bouquets of flowers and glowing candles. Among the tributes was a hand-drawn heart in the French tri-colors, torn apart, with the note, “Toujours l’amour”—Love always. It’s a feeling I’ve shared since studying law in Paris in the 1970s.

Given the enormous advances in espionage, the lessons learned from the Charlie Hebdo attack, and the very close intelligence cooperation between the U.S. and France, it would be understandable for many of those mourners to ask not just why, but how? Especially since, when it comes to spying—on the world, on Americans, on their own citizens—the French have always been très agressif.

Like the U.S. National Security Agency with its worldwide program of satellite interception called Echelon, the French have long had their version, nicknamed Frenchelon. Run by the Directorate-General for External Security and headquartered on boulevard Mortier in Paris, it has a major base near Sarlat in Périgord, and others around the country as well as overseas. Last summer it was a beneficiary of a large post-Charlie Hebdo boost in intelligence funding and new laws giving the electronic spies more power to eavesdrop on Internet communications, metadata, phone calls and hidden microphones.

But despite it all, the Paris terrorists were able to plan a very elaborate attack involving pulling disparate people together from different countries, acquiring heavy firepower and explosives, coordinating three teams, conducting extensive target surveillance, and all without being noticed by any intelligence agency, anywhere.

On Monday, CIA Director John Brennan made mention of “gaps” in what is now a standard appeal by intelligence chiefs following an intelligence disaster. After blaming the failure on “a number of unauthorized disclosures,” which could be understood to mean Edward Snowden, he then called for increasing security by reducing hard-won freedoms. But the intelligence blunders began long before Snowden leaked sensitive NSA documents, and trashing constitutionally protected freedoms for a false sense of security is not the answer.

Relying on intelligence to prevent terrorist attacks is a bit like relying on a desert mirage to find an oasis. In the U.S., despite spending hundreds of billions over the years on the National Security Agency, the Central Intelligence Agency, and the dozen other intelligence agencies, they have never prevented a major terrorist attack. They missed the first World Trade Center attack in 1993, the attack on the U.S.S. Cole, the East Africa embassy bombings, the Times Square attempted bombing, the Christmas Day underwear attempted bombing, and the Marathon bombing in Boston.

The director of NSA learned of the attacks on 9/11 not from his worldwide super-high-tech spy organization, but from his $300 office television set tuned to CNN. It later turned out that the terrorists had set up their operational base just a few miles from NSA headquarters. Other countries have been no better. In the same way, the British security agency—known as GCHQ—missed the London bombings in 2005 that killed 52, and French intelligence missed the Charlie Hebdo attacks. In their defense, as some of my NSA sources regularly tell me, there’s too much data, from too many sources, flowing way too fast.

There’s also the problem of terrorists using technology against the technospies. In addition to the growing use of end-to-end encryption, some people hoping to avoid scrutiny are turning to unusual platforms, including home video games such as Sony’s PlayStation 4, known as PS4. Posing as gamers using the Play Station Network or XBox, the terrorists can communicate over voice and data links with little fear of detection. In Belgium, where the Paris attacks were suspected to have been planned, federal home affairs minister Jan Jambon issued a warning three days before the attacks. “The thing that keeps me awake at night is the guy behind his computer, looking for messages from IS [the Islamic State] and other hate preachers,” he said. According to the leaked Snowden documents, the NSA has been so concerned about the use of online games by terrorists that it has even invented characters and infiltrated the games World of Warcraft and Second Life looking for suspicious conversations but apparently found none.

With intelligence protection largely illusionary, the only way to prevent continued terrorists attacks is for countries to re-evaluate their foreign policies. For more than a decade, Western countries have waged endless war in the Middle East producing only death, destruction, hatred—and now ISIS. At the same time, those countries have come to assume they could conduct violent regime change throughout the region—Iraq, Afghanistan, Libya, Yemen, Syria—like pieces on a chessboard, with no price to pay. For them, sadly, Paris may at last be a wake-up call. There are no Robert’s Rules of Order when it comes to war, and one man’s Hellfire missile is another man’s suicide belt.

James Bamford is a columnist for Foreign Policy Magazine, a documentary producer for PBS, and the author of The Shadow Factory: The Ultra-Secret NSA From 9/11 to the Eavesdropping on America.

Sign up for Inside TIME. Be the first to see the new cover of TIME and get our most compelling stories delivered straight to your inbox. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Contact us at letters@time.com.