The submarine-launched ballistic missile (SLBM) was a type of ballistic cruise missile operated during the Usean Rebellion of 1998.
During the Usean Rebellion, the Usean Rebel Forces acquired two Dragonet-class submarines from the Allied Forces: the Fensalir and the Folkvangr. Both submarines were equipped with SLBMs, and posed a great threat to the civilian population as well as the Allied Forces if they were to be used.
The Fensalir was discovered as it was sinking Allied Forces vessels in the waters surrounding Seals Bridge Ravine. It had not utilized an SLBM at that point, but the Allied Forces could not risk the use of the weapon, so they ordered Scarface One to destroy the submarine and the missiles with it.
The Folkvangr was not discovered until a couple of hours after Saint Ark was liberated from the Rebel Forces late in the war. It surfaced and prepared to launch an SLBM at the city. Scarface One was ordered to destroy the submarine before it could launch an SLBM. The submarine was destroyed, but it did manage to launch a specially-modified SLBM with improved speed and the ability to evade attacks like a standard fighter. Scarface One chased down the SLBM, which was closing in on St. Ark, and managed to destroy it before it hit the city.
No further use of the SLBM has been recorded.
The submarine-launched ballistic missile is a unique missile. Its warhead splits into about six smaller ballistic warheads when it approaches its target location, and the six warheads descend for a split second before detonating. The radius of each warhead's explosion isn't clear.
The SLBM, in the warhead separation and choice of warhead, does bear striking similarity to the burst missile technology. However, they do differ in some ways as well. For example, burst missiles have extreme acceleration and ascend to very high altitudes, usually too high to be engaged by anything except spacecraft. This contrasts to the SLBM, which flies very slowly, maintains a low altitude, and stays in a straight line. This is a major design flaw, as any aircraft can destroy an SLBM in flight with machine guns with ease.
The SLBM launched by the Folkvangr as a last-ditch effort was modified around the aforementioned design flaw. The missile was outfitted with technology that increased its speed and allowed it to evade attacks in a zig-zag fashion. While it was still possible for standard fighter aircraft to shoot down this modified missile, the pilot would have needed extreme skill to keep up with the missile.
- In Ace Combat: Assault Horizon Legacy, an ace flying an AH-64 Apache, callsign "HOT SNOW," annoyingly appears on the lower-left corner of the combat zone after the SLBM launches on the right edge of the combat zone. An aircraft with at least almost-maximum speed or acceleration is required to successfully shoot down the ace and still have time to destroy the SLBM.