High Quality Content by WIKIPEDIA articles! The Single Integrated Operational Plan (SIOP) is a blueprint which specifies how American nuclear weapons would be used in the event of nuclear war. At a NATO level, an agreement to use nuclear weapons envisages the United Kingdom participating in the SIOP (see below). The plan integrates the nuclear capabilities of the "triad" composed of bombers with intercontinental range, land-based intercontinental ballistic missiles (ICBM) and sea-based submarine-launched ballistic missiles (SLBM). The SIOP is a highly classified document, and has been one of the most secret and sensitive issues in U.S. national security policy. Montage of submerged submarine launch to the reentry of the multiple independently targetable reentry vehicles of a Trident missile SIOP plans were named after the fiscal year in which they come into effect. This was first officially applied to SIOP-93; prior to that, plans used a two-character alphanumeric designation.