An anti-ballistic missile (ABM) is a surface-to-air missile designed to counter ballistic missiles (missile defense). Ballistic missiles are used to deliver nuclear, chemical, biological, or conventional warheads in a ballistic flight trajectory. The term "anti-ballistic missile" is a generic term conveying a system designed to intercept and destroy any type of ballistic threat; however, it is commonly used for systems specifically designed to counter intercontinental ballistic missiles (ICBMs). Current counter-ICBM systems There are a limited number of systems worldwide that can intercept intercontinental ballistic missiles: The Russian A-135 anti-ballistic missile system (renamed in 2017 to A-235) is used for the defense of Moscow. It became operational in 1995 and was preceded by the A-35 anti-ballistic missile system. The system uses Gorgon and Gazelle missiles previously armed with nuclear warheads. These missiles have been updated (2017) and use non-nuclear kinetic interceptors instead, to intercept any incoming ICBMs. The Israeli Arrow 3 system entered operational service in 2017. It is designed for exo-atmosphere interception of ballistic missiles during the spaceflight portion of their trajectory, including those of ICBMs. It may also act as an anti-satellite weapon. The Indian Prithvi Defence Vehicle Mark 2 has the capability to shoot down ICBMs. It has completed developmental trials and is awaiting the Indian government's clearance in order to be deployed. The American Ground-Based Midcourse Defense (GMD) system, formerly known as National Missile Defense (NMD), was first tested in 1997 and had its first successful intercept test in 1999. Instead of using an explosive charge, it launches a hit-to-kill kinetic projectile to intercept an ICBM. The current GMD system is intended to shield the United States mainland against a limited nuclear attack by a rogue state such as North Korea. GMD does not have the ability to protect against an all-out nuclear attack from Russia, as there are 44 ground-based interceptors deployed in 2019 against any crossing projectiles headed toward the homeland. (This interceptor count does not include the THAAD, or Aegis, or Patriot defenses against directly incoming projectiles.) The Aegis ballistic missile defense-equipped SM-3 Block II-A missile demonstrated it can shoot down an ICBM target on 16 Nov 2020. In November 2020, the US launched a surrogate ICBM from Kwajalein Atoll toward Hawaii in the general direction of the continental US, which triggered a satellite warning to a Colorado Air Force base. In response, launched a missile which destroyed the surrogate ICBM, while still outside