The Antarctic Treaty and related agreements, collectively called the Antarctic Treaty System or ATS, regulate international relations with respect to Antarctica, Earth's only continent without a native human population. For the purposes of the treaty system, Antarctica is defined as all of the land and ice shelves south of 60°S latitude. The treaty, entering into force in 1961 and currently having 49 signatory nations, sets aside Antarctica as a scientific preserve, establishes freedom of scientific investigation and bans military activity on that continent. The treaty was the first arms control agreement established during the Cold War. The Antarctic Treaty Secretariat headquarters have been located in Buenos Aires, Argentina, since September 2004.
The main treaty was opened for signature on December 1, 1959, and officially entered into force on June 23, 1961. The original signatories were the 12 countries active in Antarctica during the International Geophysical Year (IGY) of 1957–58. The 12 countries had significant interests in Antarctica at the time: Argentina, Australia, Belgium, Chile, France, Japan, New Zealand, Norway, South Africa, the Soviet Union, the United Kingdom and the United States. These countries had established over 50 Antarctic stations for the IGY.