In an exercise that would resonate with historical instances of David defeating Goliath, a French nuclear attack submarine, the Saphir, part of the Rubis class, managed a simulated takedown of the USS Theodore Roosevelt, one of the largest nuclear-powered aircraft carriers in the world.

This event unfolded during a joint Franco-US naval exercise off the coast of Florida in March 2015.

The first phase of the exercise was standard procedure, with the Saphir integrating with U.S. Navy forces to detect and track imaginary enemy submarines.

But the second phase would prove more dramatic. The Saphir switched allegiances, teaming up with U.S. Navy P-3C Orion and P-8 Poseidon maritime patrol aircraft to hunt down and attack the Roosevelt.

As the war game progressed and theoretical hostilities escalated, the Saphir was given the green light to ‘engage’ the carrier.

According to the scenario, the French submarine ‘sank’ the Roosevelt and ‘most’ of its escorts, a feat that, if real, would have resulted in significant losses for one of the U.S. Navy’s most potent strike groups.

The shockwaves from this exercise were not simply confined to the waters where they took place. The news of this simulated victory by the Saphir—measuring a fraction of the Roosevelt’s size and cost—revealed a critical vulnerability in the Navy’s carrier defenses.

The exercise’s outcome was so jarring that reports of the event were swiftly removed from the French Navy’s blog, indicating perhaps an effort to manage the optics of the incident around a key NATO ally.

This scenario underlines a truth in military strategy: expense and complexity do not necessarily equate to invulnerability.

The history of warfare is rife with examples where cheaper, simpler technologies have upended advanced military systems.

In Iraq, improvised explosive devices (IEDs) exacted a heavy toll on U.S. forces; in Afghanistan, shoulder-launched missiles decimated Soviet aircraft; and the USS Cole was severely damaged by a small boat laden with explosives off the coast of Yemen.

The ‘sinking’ of the Roosevelt by the Saphir carries a warning that must not be dismissed. As U.S. Naval Institute News reported, the Carrier Strike Group 12, which includes the Roosevelt, had deployed for a Middle East operation.

The Rubis-class submarine, despite being the smallest nuclear combatant at sea, equipped with only four torpedo tubes and torpedoes with a 551-pound warhead, managed to ‘destroy’ the carrier and its escorts.

This outcome is a sobering reminder that despite the multi-billion dollar investments and advanced technologies employed by carrier strike groups, they are not immune to threats lurking beneath the waves.

The incident served as a stark wake-up call for the U.S. Navy, whose anti-submarine warfare (ASW) capabilities reportedly declined after the Cold War.