Second Strike Capability refers to a nation's ability to respond to a nuclear attack with its own nuclear retaliation. This capability is crucial for maintaining a credible deterrent against potential aggressors, as it ensures that even after suffering an initial strike, a country can still inflict significant damage on the attacker. This concept is often associated with nuclear powers like the United States and Russia, which maintain a variety of delivery systems, such as submarines and intercontinental ballistic missiles (ICBMs). By having a reliable second strike capability, these nations aim to prevent nuclear war through the assurance of mutual destruction.