Hangzhou clash sheds light on US Navy countermeasures
Ten Houthi militants were killed in a clash with US helicopters and armed guards aboard a commercial vessel in the Red Sea.
In the latest episode of a simmering conflict in the region, the Houthis launched three anti-ship ballistic missiles at the Maersk Hangzhou, a Singapore-flagged cargo vessel.
One missile hit the ship, causing damage but no casualties, while the other two were shot down by the USS Gravely.
The US said on Sunday that a naval task force created last month to protect shipping had shot down four ballistic missiles and 17 drones fired by the Iran-backed Yemeni militia.
The USS Gravely responded to the Maersk Hangzhou’s distress call on Sunday after militants in boats shot at the ship from about 20 metres, the US military Central Command said.
“A contract embarked security team” exchanged fire with the boats while distress calls were made, Centcom added. Many shipping companies pay private security companies such as Ambrey to guard their vessels in the Red Sea.
Helicopters, reportedly from the USS Dwight D Eisenhower aircraft carrier, destroyed three of the Houthi boats “in self-defence”, Centcom said.
The clash sheds light on the evolution of American measures to counter “boat swarms”, which have long been feared by the US Navy operating in narrow waterways, particularly the Strait of Hormuz, where Iran operates armadas of small, fast boats.
The US’s concern stems from a military exercise in 2002, the Millenium Challenge, during which an imaginary opponent – loosely based on Iran or Saddam Hussein’s Iraq – swarmed US ships with explosive-laden attack boats, “sinking” 19 naval vessels.
Since then, the US has reconfigured several weapons systems designed during the Cold War.
Centcom did not say what weapons were used against the Houthi boats, but the helicopters responding to the distress call were Sikorsky SH-60 Seahawks, which are armed with machineguns, missiles and rockets modified for naval use.
The SH-60 can carry a variant of the Hellfire missile, designed to destroy Soviet tanks, but tested in 2015 with a series of modifications to hit “high-speed manoeuvring surface targets”, according to a 2016 US Army report, which also said the weapon has a fragmentation warhead intended to destroy “boats in swarm attacks”.
The helicopter can also carry 70mm rockets modified with laser guidance.
The rockets, which have been used extensively since the Vietnam War, were successfully tested in 2013 against fast-moving boats.
According to a US Naval War College study, they are one of the cheapest available options for tackling small boats, with each missile costing about $20,000, and can also be mounted on naval vessels.
Another ship-mounted missile, the BGM-176B Sea Griffin, which has a range of up to 15km, has been extensively tested against small boats, but is more expensive, with each missile costing about $150,000.
US aircraft can also be fitted with guided cluster bombs, while anti-missile systems including the Phalanx, which fires thousands of cannon shells per minute, have also been adapted to fire at surface vessels.
For larger threats, like antiship ballistic missiles and even low-flying cruise missiles – which are in the Houthis’ arsenal – US warships are equipped with the Aegis defence system.
The heavily upgraded system, which entered service in 1981, has proven adept at shooting down fast-moving ballistic missiles and can now counter complex attacks, involving different weapons used at once, designed to overwhelm defences.
Last month, US naval forces in the Pacific conducted an exercise with the Aegis system against ballistic missiles and mock cruise missiles, shooting down targets in a simulated attack, using two different types of interceptor missiles.