Sea-Bed Treaty

The Sea-Bed Treaty—formally the Treaty on the Prohibition of the Emplacement of Nuclear Weapons and Other Weapons of Mass Destruction on the Sea-Bed and the Ocean Floor and in the Subsoil Thereof—was opened for signature on 11 February 1971 in Washington, London, and Moscow, and entered into force on 18 May 1972. It was negotiated through the Conference of the Committee on Disarmament (CCD) in Geneva and is one of several Cold War-era treaties extending arms control into specific environments, alongside the Antarctic Treaty (1959) and the Outer Space Treaty (1967).

Under Article I, parties undertake not to emplant or emplace on the seabed, ocean floor, or subsoil beyond the outer limit of a 12-nautical-mile coastal zone any nuclear weapons or other weapons of mass destruction, or structures, launching installations, or facilities specifically designed for storing, testing, or using such weapons. The 12-mile zone is defined by reference to the 1958 Convention on the Territorial Sea and the Contiguous Zone.

Article III provides for verification through observation by other state parties, with disputes referable to the UN Security Council. Article VII requires review conferences; review conferences were held in 1977, 1983, and 1989.

The treaty has notable limits. It does not prohibit:

• Submarines carrying nuclear weapons that transit or rest on the seabed temporarily.
• Conventional weapons or military installations on the seabed.
• Anti-submarine warfare detection systems.

These gaps reflected compromises between the US and USSR, both of which operated ballistic-missile submarines and seabed surveillance systems (such as SOSUS).

As of the most recent depositary records, the treaty has well over 90 states parties, including all five NPT nuclear-weapon states. France and China are not parties. The treaty remains in force indefinitely and is considered a foundational instrument of the wider non-proliferation regime, though it receives less attention than the NPT or the Comprehensive Nuclear-Test-Ban Treaty.