COLUMN | Houthi attacks show asymmetrical sea warfare is the way ahead [Naval Gazing]

Attacks by Yemen's Houthi rebels on merchant shipping in the Red Sea, the Indian Ocean, the Gulf of Aden, and the Arabian Sea continue apace. The Iran-backed Houthis are very well equipped with multiple attack drones and with anti-shipping cruise and ballistic missiles. These weapons are based mainly on old Chinese-designed weaponry, reverse-engineered and modified by Iranian technicians.

This ongoing threat has resulted in the provision of protection to these vessels becoming a major commitment for US, UK, and EU naval forces. Navies are therefore having to shift much of their operational focus from conventional blue water operations to countering long-term asymmetrical threats in the littoral, with tactics and armament needing to be adapted accordingly.

Attacks on shipping, launched from inland by well-equipped irregular forces, are problematic to defend against. The Houthis' weapons and radar systems are very mobile and therefore difficult for even intensive aerial surveillance to keep track of.

Numerous strikes by US and British warplanes against missile launching and sensor systems within Yemen have therefore had only limited success. Such operations have also been subject to political restrictions.

Some conventional sea warfare doctrines have long recommended the following tactics to facilitate the protection of merchant vessels in shipping lanes. Neither of them, however, are well-suited to the countering of projectiles launched from well inland:

1. Convoys – Large formations of merchant ships would present the Houthi rebels with a concentration of targets, likely resulting in multiple strikes, which escorting warships would find difficult to counter.
2. Patrolled shipping lanes – The securing of sea lanes would demand the sustained deployment of very large number of escorts. However, it is already proving very difficult, owing to decades of cutbacks to naval forces, to field frigates and destroyers in sufficient numbers to provide existing levels of protection.

Countermeasures

Existing surveillance and fire control radars mounted on escort vessels have reportedly been effective in enabling the destruction of many incoming projectiles. Since October 2023, at least 100 attacking drones and missiles have been downed. Most were shot down by SM-3, SM-6. Aster, Sea Viper, and Sea Ceptor, ship-launched, air defence missiles, some by gunfire, and some by air-to-air missiles launched from naval fighter-bombers and helicopters.

Missiles are very expensive, though, with a weapon such as Aster reportedly costing upwards of US$1.3 million per piece and in short supply. Therefore, more cost-effective methods of interception and destruction have been sought out, with some existing projects being brought forward by way of an influx of new funding:

1. Directed energy weapons – Ship-mounted laser weapons such as the UK DragonFire and the US HELIOS and HELCAP systems are at an advanced stage of development and should be in service within about two years. These systems receive target information from the ship's radar, and by using rapidly-moving, multiple, moveable mirrors and lenses, these concentrate and aim the laser beam so as to disable the propulsion system of the targeted projectile. One "shot" from a directed energy weapon reportedly costs about US$13.
2. Electronic warfare – Currently under development are advanced, trainabl, decoy launchers, such as the SEA Ancilia.  These systems enable the rapid firing of multiple missile decoy rounds in response to incoming threats. The decoys consist of explosive rounds containing silver paper, cut to specific lengths in order to confuse or deceive incoming radar-guided projectiles, and high-intensity flares that are intended to seduce heat-seeking projectiles away from their intended targets.
3. Missile upgrades – "Soft kill" options as discussed above are increasingly effective, but they are not a panacea. They are restricted to line-of sight firing and limited by range and meteorological factors. Air defence missiles are therefore still required.

In order to cope with the growing demands of asymmetrical sea warfare, system enhancement programmes are in hand, including the installation of multiple vertically-launched Patriot missiles on US Navy escorts, as well as major upgrades to the performance and lethality of Aster and Sea Viper systems on EU and UK frigates and destroyers.

Likely future asymmetrical threats

Analysts believe that rapid technological advance is resulting in the surging availability of cheap and effective anti-shipping weaponry, and that it is certain that asymmetrical threats to shipping, particularly from non-state actors operating with the covert backing of anti-western national alliances, are certain to multiply. Areas that could potentially be vulnerable in future to this type of warfare include the Arabian Gulf, the North African coast, and the Baltic.