Limited first strike

The limited first strike policy is a military doctrine referring to the use of nuclear weapons in modern military strategy. In essence, this policy states that, in the event of an attack by another country by conventional (that is to say, non-nuclear) means, the defending country's response would be to retaliate using some amount of nuclear force. "First strike" refers to the first use of nuclear weapons in a war as an act of retaliation, not to a pre-emptive or aggressive attacks using nuclear force.

For example, suppose that the small country A and the larger country B have rocky relations. Country A, being smaller, does not have the resources needed to build a large conventional army, so it adopts the "limited first strike policy". Thus, if country B attacks country A with its conventional army, country A will counter-attack with its nuclear weapons.

The idea is that the "limited first strike policy" serves as a deterrent to possible aggressors for fear of nuclear war.