An intercontinental ballistic missile (ICBM) is a guided ballistic missile with a minimum range of primarily designed for nuclear weapons delivery (delivering one or more thermonuclear warheads). Similarly conventional, chemical and biological weapons can also be delivered with varying effectiveness, but have never been deployed on ICBMs. Most modern designs support multiple independently targetable reentry vehicles (MIRVs), allowing a single missile to carry several warheads, each of which can strike a different target.