Summary and Key Points: HNLMS Walrus cost less than a single Aegis escort. It was a Dutch diesel-electric boat with a submerged displacement of 2,800 tons, one of 4 built in Rotterdam and commissioned in the early 1990s, and modern estimates put its price between $340,000,000 and $500,000,000. In February 1999, it was assigned to Joint Task Force Exercise 99-1, the largest concentration of American naval power since the 1990 Gulf War buildup — roughly 24,000 personnel, 15,000 of them at sea. Running submerged on batteries, using the ocean’s thermal layers to hide, the Walrus passed through the anti-submarine screen around USS Theodore Roosevelt and fired simulated torpedoes from about 4,000 yards. It was credited with sinking the carrier and, by its commander’s account, 7 escorting warships. Then it closed to roughly 1,500 yards and passed near the carrier itself — a maneuver with no purpose except to demonstrate that the most heavily defended warship on earth had never once held contact on the boat that killed it.
A Diesel Submarine That Cost Less Than 1 Escort Ship “Sank” a US Supercarrier and 7 Other Warships. It Was 1999, and It Keeps Happening
In 1999, a Nimitz-class aircraft carrier represented roughly $4.5 billion of American shipbuilding, before counting the air wing on its deck or the cruisers, destroyers, frigates, and attack submarine assigned to protect it, a formation whose full value ran toward $20 billion.
The submarine that beat all of it was HNLMS Walrus, a Dutch diesel-electric boat of 2,800 tons submerged, one of four built in Rotterdam and commissioned in the early 1990s, whose cost modern accounting puts between $340 million and half a billion dollars in the era’s money.
Take the highest figure and the submarine still cost less than a single Aegis escort and roughly a ninth of the carrier alone; take the lowest, and the ratio approaches thirteen to one against the flagship, and forty to one against the formation.
Aircraft carrier USS Theodore Roosevelt (CVN 71) passes Fort Worden before its arrival at Naval Base Kitsap in Bremerton, Washington, July 22, 2021.
During a major exercise in the winter of 1999, that cheap boat penetrated the strike group of USS Theodore Roosevelt, simulated torpedo attacks credited with sinking the supercarrier and, by its commander’s account, seven escorting warships, and then proved the point in the most contemptuous way available to a submariner.
This is the complete account of what happened, why it was not a fluke, and why the same result has kept arriving up to the present day.
The Exercise Nobody Briefed Them For
The event was Joint Task Force Exercise 99-1, conducted in conjunction with the Theater Missile Defense Initiative 1999 and recorded as JTFEX/TMDI99.
It was enormous: roughly 24,000 personnel, 15,000 of them at sea, in what was described as the largest concentration of American naval power since the 1990 Gulf War buildup, spread across Atlantic waters running from Norfolk, Virginia, down toward Puerto Rico.
The Navy announced the exercise through its own wire service in January 1999 as a workup for the Theodore Roosevelt battle group and the Kearsarge amphibious ready group.
The Netherlands contributed one submarine.
Its commander, Jan Hubert Hulsker, later recalled arriving in the United States for the exercise instructions and, on the day of departure, receiving only a few sheets of paper, no briefing, no presentation.
Walrus-Class Submarine NATO Image
Walrus-Class Submarine. Image Credit: Creative Commons.
Walrus-Class Submarine. Image Credit: Creative Commons.
The Dutch boat sailed into the largest American naval formation assembled in nearly a decade with a handful of pages and its own quiet, and the thinness of the welcome turned out to be the last advantage the defenders gave away for free.
The Attack: Walrus vs. the Aircraft Carrier
What the Walrus did with the assignment became one of the defining stories of modern undersea warfare, though it took seventeen years to become public, emerging only when Hulsker gave his account to the Dutch naval press in 2016.
Running submerged on battery power, the boat exploited the ocean’s thermal layers, the bands of differing temperature and salinity that bend and trap sound, to hide from the strike group’s sonar while working into the formation.
A diesel-electric submarine on batteries generates no reactor pumps, no continuous machinery signature, almost nothing for a passive sonar operator to hold, and the Walrus used that silence to pass through an anti-submarine screen built around the assumption that submarines make noise.
Inside the screen, the boat conducted simulated torpedo attacks from about 4,000 yards and was credited with killing the Theodore Roosevelt and, in the commander’s telling, seven escorts besides, a toll that would have decapitated the entire formation had the torpedoes been real.
Rather than withdrawing, the Walrus then closed to roughly 1,500 yards and passed near the carrier itself, a maneuver with no tactical purpose except demonstration: proof, recorded in the exercise’s own reconstruction, that the most heavily defended warship on earth had never held contact on the boat that killed it.
The submarine left the area undetected.
The fuller retellings of the episode note that the exercise ran from February 1999, and no American account has publicly disputed the Dutch one.
What the Costs Actually Bought
The carrier’s billions bought catapults, ninety aircraft, nuclear endurance, and command facilities, none of which help detect a battery-powered submarine in layered water.
The escorts’ billions bought area air defense first and submarine hunting second, with sonar suites and crew training tuned, in 1999, to the loud Soviet nuclear boats of the previous war.
The Walrus’s few hundred million bought exactly one thing the formation could not answer: near-silence, plus a crew from a navy that practices in the cramped, shallow, acoustically filthy waters of the North Sea, where hiding is the whole game.
The asymmetric cost curve, as analysts came to call it after the later Swedish episode, is not that cheap things beat expensive things, but that a platform optimized for one narrow task can defeat a platform optimized for twenty, at a fraction of the price, whenever the fight happens on the narrow task’s terms.
A torpedo does not check the displacement of the ship that launched it, and the class that fired this one will serve the Netherlands into the 2030s, when replacement boats arrive.
Aircraft Carriers Keep Getting ‘Hit’ In Drills
If the Walrus were a single data point, the Navy could file it under bad days. Sadly, this just keeps occuring, over and over again.
In 2005, the Swedish submarine HSwMS Gotland, a 1,600-ton boat built for roughly $100 million and equipped with Stirling air-independent propulsion that let it stay submerged and silent for weeks, was pitted against the strike group of USS Ronald Reagan, then the Navy’s newest carrier at about $6.2 billion.
The Gotland maneuvered into a firing position and repeatedly executed simulated attacks on the carrier across multiple runs without being detected.
The good news is the Navy might have seen this coming, and it leased the submarine (before the sinking drill occurred) and its Swedish crew for two years and kept them off San Diego as a sparring partner, rebuilding anti-submarine skills that had atrophied since the Cold War with refreshed towed arrays, the P-8 transition, multistatic sonobuoy tactics, and a standing program of exercises against allied diesel boats, a response cataloged in various outlets
In 2006 this seemed to happen all over again, when a Chinese Song-class diesel boat surfaced within torpedo range of USS Kitty Hawk’s battle group in the Pacific, having approached undetected.
And in 2015 it happened to the Theodore Roosevelt a second time, when the French nuclear attack submarine Saphir, a small 1970s-era boat, threaded the carrier’s screen off Florida and fired simulated torpedoes into her, an episode the French navy briefly publicized and then deleted, and which this publication has treated in full.
One carrier, two navies, sixteen years apart, same result.
The pattern spans four decades and four navies, and every kind of quiet boat, which is precisely what makes it a pattern rather than an anecdote.
This also happened in many other drills and simulations we have never heard of, according to many US Navy retired officers I have spoken to over the years.
A Drill Is No War
An exercise is not a war, and the differences are not small.
Exercise geography is a box: the submarine usually knows roughly where the carrier will be, because the scenario requires the two to meet, which gifts the boat the hardest part of real submarine warfare: finding a 30-knot ship in an ocean.
Carriers in workup exercises often run constrained courses at moderate speeds, sacrificing their best defense, which is sprinting fast enough that a diesel-electric boat can never reach a firing position.
Simulated kills are adjudicated generously, escorts operate under peacetime safety rules, and no submarine in these events faces the thing that makes real attacks on carriers historically rare, which is dying.
All of that is true, and the counterargument is shorter: the defenders knew a submarine was hunting them, inside a defined box, with their full screen deployed, and lost anyway, repeatedly, to four different navies.
The constraints cut both ways, and the Navy’s own behavior is the tiebreaker, because institutions do not lease foreign submarines for two years to study a problem their exercises invented.
Why 2026 Makes It Worse, Not Better
Everything that made the Walrus dangerous in 1999 has proliferated since.
Air-independent propulsion, which the Gotland demonstrated, is now standard equipment on German, Swedish, Japanese, South Korean, and Chinese boats, and China’s Yuan-class AIP submarines exist in numbers within a fleet of dozens of conventional boats built precisely for the shallow, loud, layered waters of the western Pacific where American carriers would have to operate in a Taiwan fight.
The US Navy, meanwhile, fields eleven carriers and can usually deploy four, each one a concentration of value that grows with every budget cycle, and China has been rehearsing against them openly, building carrier-shaped targets in its desert for its missile force while its submarine force multiplies beneath the same problem.
The lesson of 1999 was never that carriers are obsolete, but more something like this: a quiet submarine in the right water, on the defensive terms it chooses, can reach the most protected ship in the world, and the price of admission has been falling since the day the Walrus sailed with its few sheets of paper.
About the Author: Harry J. Kazianis
Harry J. Kazianis (@Grecianformula) was the former Senior Director of National Security Affairs at the Center for the National Interest (CFTNI), a foreign policy think tank founded by Richard Nixon based in Washington, DC. Harry has over a decade of experience in think tanks and national security publishing. His ideas have been published in the NY Times, The Washington Post, The Wall Street Journal, CNN, and many other outlets. He has held positions at CSIS, the Heritage Foundation, the University of Nottingham, and several other institutions related to national security research and studies. He is the former Executive Editor of the National Interest and the Diplomat. He holds a Master’s degree focusing on international affairs from Harvard University.
