After much effort and long negotiations, on July 14, 2015, the Joint Comprehensive five-plus Action (JCPA) agreement was concluded between the Islamic Republic of Iran and the five plus one states, and the Security Council's nuclear sanctions against Iran were lifted. Following the change of government in the United States, on May 18, US President Donald Trump officially announced his withdrawal from the JCPA and the return of sanctions. On January 7, 2020, Iran announced a fifth and final step in reducing its obligations under this treaty after four stages of reducing its commitments. According to Iran's statement, the Islamic Republic of Iran no longer faces any restrictions in its field of operations (including enrichment capacity, percentage of enrichment, amount of enriched material, and research and development). To examine and analyze the legitimacy of Iran's suspensions, it is necessary to interpret these commitments and obligations under JCPA, which is possible by using the hermeneutic principles of interpretation and the rules of interpretation in the Vienna Convention on the Law of Treaties (1969). By applying the context of this treaty, the legal principles applicable to it, including the principle of good faith and pacta sunt servanda, examining the circumstances of the time of the conclusion of the treaty, it is concluded that Iran's suspensions are of international legitimacy. In addition, Iran's good faith has been proven by emphasizing the full reversibility of the obligations based on the JCPA agreement.