The Antarctic Treaty was signed in Washington on 1 December 1959 by the twelve countries whose scientists had been active in and around Antarctica during the International Geophysical Year (IGY) of 1957-58. It entered into force in 1961 and has since been acceded to by many other nations. The total number of Parties to the Treaty is now 49. Antarctica shall be used for peaceful purposes only (Art. I) Freedom of scientific investigation in Antarctica and cooperation toward that end … shall continue (Art. II). To promote the objectives and ensure the observance of the provisions of the Treaty, "All areas of Antarctica, including all stations, installations and equipment within those areas … shall be open at all times to inspection " (Art. VII).