The submarine struck the ship with a torpedo, U.S. Defense Secretary Pete Hegseth said, resulting in “quiet death”.
The event marks the first time a U.S. submarine has launched a torpedo in combat or engaged and destroyed a ship since the second world war.
Why is this old weapon reappearing now? And for that matter, what are torpedoes? Can ships defend against them, or even see them coming?
What are torpedoes, and how do they work?
Torpedoes have changed little over the years in terms of their concept and their operation. Simply put, a torpedo is effectively a small, unmanned submersible – a kind of hybrid of a mini-submarine and a missile, designed to attack both submarines and surface ships.
However, they have been modernised to an extent. Torpedoes today are generally “dual purpose”, designed to attack and destroy both ships and submarines. Single-purpose torpedoes are less commonly seen, but given their specialised nature are often more lethal.
Torpedoes are initially connected to the launching submarine by a wire or fibre-optic cable transmitting targeting data. These wires are designed to be “cut” as the torpedo gets close to its target, with the torpedo then switching on its own active sonar to steer the rest of the way.
Exactly how far torpedoes can be fired is highly classified information, but it may be tens of kilometres. It depends partly on how the torpedo is propelled – either with an electric motor (more common) or a fuel-powered one.
Electric motors are generally preferable, given their ability to accelerate instantly and achieve higher speeds. However, the range is generally considered to be lower than fuel-propelled torpedoes.
Why torpedoes are still in use today
Torpedoes are quite old and in many ways quite simple compared with more modern weaponry. However, they remain the primary armament of attack submarines.
As the name suggests, attack subs are designed to hunt and destroy other submarines, surface combatants (warships) and, if necessary, commercial vessels.
Other types of submarines such as ballistic missile submarines (designed for retaliatory nuclear strikes) and guided missile submarines (designed to fire guided missiles) also generally carry torpedoes for self-defence.
Submarines are by their nature stealthy. They are designed to sneak in close to their target undetected, and launch surprise attacks while remaining submerged.
To fire an air missile, a submarine needs to come close to the surface and risk detection. So torpedoes, which can be fired underwater, remain the perfect offensive weapon for submarines.
Torpedoes can also be delivered by aircraft, usually to strike at submarines where airborne missiles can’t reach. Aircraft typically use missiles to strike surface ships, as an aircraft would need to make a risky close approach to get within torpedo range.
How do warships detect and protect themselves from torpedo attack?
Beneath the sea, visibility is low and the radio waves used for radar don’t travel far. The primary tool for detecting submerged objects is sonar.
Sonar systems use sound, which travels faster and further through water than air.
There are two kinds of sonar: passive and active. Passive sonar listens quietly for engine noise, or transient sounds such as a torpedo tube being opened.
Active sonar generates a loud “ping” or series of pings and then listens for echoes. The initial pulses of noise reflects off objects to effectively paint an image, in a process known as echolocation.
The use of active sonar is generally avoided unless absolutely necessary, as it gives away the sonar