The Royal Navy has tested a boat killer missile, the Martlet, in the Irish Sea. The anti-ship missile, also known as the Lightweight Multirole Missile (LMM), was fired from the Royal Navy’s Type 23 frigate HMS Sutherland, an an official statement said the target boat took a direct hit in the Irish Sea.

The firing assumes significance following recent reports that a Royal Navy ship had to warn off Iranian gunboats that had tried to "impede" a British oil tanker.

Four Martlet missiles, designed to be fired by Wildcat helicopters to defeat terrorists and suicide bombers, were fired at a fast-moving speedboat, within the Aberporth Range at the southern end of Cardigan Bay off the Welsh coast, during the test. Experts, according to the Defense Post, say the modular LMM can use different precision guidance modes, including laser beam riding and laser designation, and carries a 3 kg dual-effect blast fragmentation and shaped charge warhead.

Built by Thales, the Martlet is just four feet long and weighs under 29 pounds, making it ideal for attachment to the main deck gun turret. It uses multi-mode seekers, with beam-riding laser guidance and an infrared seeker in the terminal phase of flight.

Royal Navy Lieutenant Commander George Blakeman, who is the weapon engingeer officer aboard Sunderland,  in a statement said the current defense against fast inshore attack craft, the 30mm gun, is highly effective for closer range engagements. “By adding the missile to the gun mount, it is anticipated it will extend the reach of the ship’s defensive systems,” he said. The commander added that this is the key to successful defense against fast craft using swarm attack tactics.

The statement said the testing also included the firing of a 30mm gun to successfully demonstrate that there was no loss of accuracy from the addition of the missile launcher. “The first of the four missile launches was specifically to see if the the backblast and shock of firing would damage the cannon, the weapon mount, or the ship, which it did not,” the statement explained.

During last week's incident, the HMS Montrose had trained its 30 mm cannon on the Iranian boats. 

Iran has invested in developing asymmetric weapons, which include fast attack boats that can swarm and overwhelm bigger ships, to make up for its weakness against bigger and more sophisticated western navies. The Iranian navy and the Revolutionary Guards Corps naval force have missile gunboats and surface craft that are armed with advanced torpedoes, mines, anti-ship missiles and anti-aircraft guns.