What was China's first veto as a permanent member of the Security Council used to prevent?

China's first veto as a permanent member of the United Nations Security Council was used to prevent the admission of Bangladesh into the UN. This veto occurred in 1972, highlighting China's position on territorial and political issues in relation to its foreign policy priorities.

At the time, China was concerned about the implications of recognition and the geopolitical influences in South Asia, particularly regarding India's role and the ongoing tensions in the region. The decision to veto was part of China's broader strategy to assert its influence and protect its interests, especially considering the complex realities of diplomatic relations in the context of the Cold War era.

In contrast, the other options pertain to different historical contexts that do not align with China's first veto record. The admission of South Korea, for instance, was a significant action in the Cold War framework, while the formation of UN peacekeeping forces and decisions regarding the Secretary-General relate to broader UN operational matters that did not involve China's initial expression of its veto power.