In April 2015, Boeing unveiled a modified version of the RGM-84 it called the Harpoon Next Generation. It increases the ship-launched Harpoon missile's range from the Block II's 70 nmi (81 mi; 130 km) to 167. 5 nmi (192. 8 mi; 310. 2 km), along with a new lighter 300 lb (140 kg) warhead and a more fuel-efficient engine with electronic fuel controls. Boeing offered the missile as the U. S. Navy's Littoral Combat Ship frigate upgrade over-the-horizon anti-ship missile as a cost-effective missile upgrade option; complete Next Gen Harpoons would cost approximately as much as a Block II at $1. 2 million each, with upgrades for an existing missile costing half that. The version is also called the Harpoon Block II + ER. Boeing claims the Block II+ ER is superior to the Naval Strike Missile through its improved turbojet giving it greater range and active radar-homing seeker for all-weather operation, as well as a lighter but "more lethal" warhead. Test shots in 2017 had been confirmed. In May 2017, Boeing revealed it was no longer offering the upgraded Harpoon for the frigate OTH missile requirement, but would continue development of it.