Détente refers to the time in the 1960s and 1970s when tensions eased between the two superpowers, the United States and the Soviet Union, as they attempted to co-operate and avoid conflict in the Cold War. A clear demonstration of an 'easing' of tensions is demonstrated by a number of treaties initiated and signed by the superpowers. For example, the 1968 Nuclear Non-Proliferation Treaty, whereby powers with nuclear weapons agreed not to provide any other countries nuclear technology. This was a clear attempt to reduce the mechanisms by which conflict may arise. Another example is the 1972, SALT1 Treaty (Strategic Arms Limitation Talks), whereby the United States and the Soviet Union both agreed to limit their anti-ballistic missiles and bombers. The imposition of limitations on their nuclear capabilities seems to further demonstrate a clear shift toward more co-operative relations between the two superpowers and thus an easing of tensions. However, it is important to recognise many of the treaties signed during this period, the previous two examples included, were largely ineffectual. The Nuclear Non-Proliferation Treaty did not achieve its intended objective, failing to prevent other countries from developing nuclear weapons. Further, neither the United States or the Soviet Union adhered to the SALT1 Treaty, as neither side reduced their conventional weapons. Negotiations started for SALT2, in an attempt to build on SALT1, however relations worsened and the talks collapsed. The failures of these treaties clearly highlights the fundamental limitations in asserting that there was an 'easing' of tensions in the Cold War during the détente period. Rather, much of the success of period was limited to symbolic achievements, such as the US table tennis team playing in China in 1971, and in 1975 when the Russian and American spacecraft docked in space, which was the first joint US-Soviet space expedition.