On this day 50 years ago, on July 30, 1975 (June 22, 1975 lunar calendar), the Conference on Security and Cooperation in Europe was held in Helsinki. From July 30 to August 1, 1975, the Conference on Security and Cooperation in Europe was held in Helsinki. Representatives of 35 countries from Europe, the United States and Canada participated in the conference and signed the Final Act. It includes: "Certain documents on confidence-building measures and security and disarmament", "Cooperation in economic science and technology and the environment", etc. The Soviet Union is most concerned about European security issues and hopes to fix the status quo of European borders through the CSCE. The Final Document, in a declaration of principles governing the relations of the participating states, sets out 10 principles for the conduct of relations between the participating states, which specifically mention "the inviolability of borders" and "the prohibition of the use or threat of use of force." The Document on Confidence-Building Measures and Security and Disarmament also stipulates that when participating states hold military exercises with more than 25,000 troops within 250 kilometers of the shared border with other participating states, they shall notify the participating states 21 days in advance and invite them to send observers to watch the exercises. In discussing the issue of "Economic, Scientific and Technological and Other Cooperation", the Soviet Union hoped that through this cooperation, Western technology and funds would be introduced. The Western countries both want to carry out economic infiltration of the Soviet Union and Eastern Europe, and they want to use it as a means of exerting pressure. Comments: The Western countries at this meeting both want to carry out economic infiltration of the Soviet Union and Eastern Europe, and they want to use it as a means of exerting pressure.