A Submarine-Launched Ballistic Missile (SLBM) is a type of missile that is launched from submarines. These missiles are designed to carry nuclear warheads and can strike targets at long distances, making them a key component of a country's strategic defense system. SLBMs are typically housed in vertical launch tubes within the submarine, allowing for stealthy deployment. SLBMs enhance a nation's second-strike capability, meaning they can retaliate after a nuclear attack. This capability is crucial for deterrence, as it discourages potential adversaries from launching an attack. Countries like the United States and Russia have developed advanced SLBM systems to ensure their national security.