What core international principle is most fundamentally challenged by the UN Security Council’s P5 veto power?

💡 Explanation:

The permanent members (P5) veto power fundamentally challenges the principle of 'sovereign equality of all member states' enshrined in Article 2 (1) of the UN Charter. The veto grants five states a unique and unequal legal status, allowing them to unilaterally block action supported by the vast majority of members, thus creating an oligarchical decision-making structure for global peace and security.