The nuclear program of the Islamic Republic of Iran has become one of the main axes of regional and international interactions over the past three decades. Despite Iran’s emphasis on its peaceful nature and its reliance on international law, this program has always faced reactions from neighboring countries and major powers. Despite much research and study on various aspects of the Iranian nuclear program in international political studies, little attention has been paid to the effective role of Saudi Arabia in it. Saudi Arabia, as Iran’s regional rival and America’s main ally in the Persian Gulf, has adopted varying positions towards this program. This article examines the developments in Saudi Arabia’s foreign policy in four time periods against the Iranian nuclear program using the theoretical framework of “neoclassical realism.”
Theoretical Framework of Neoclassical Realism: This theory, by combining two levels of micro and macro analysis, examines the impact of the international structure and the perceptions of political leaders on foreign policy decisions. From this perspective, Saudi Arabia's behavior is influenced by external factors (such as regional competition and the international system) and internal factors (such as the threat perception of leaders, public opinion, and decision-making structures).
As the most important and largest Arab state in the Persian Gulf and also the most important US ally in the region, the Saudi government was most influenced by the security perceptions of its officials regarding Iran's nuclear and regional threats. When the United States took an aggressive approach to Iran's nuclear program, Saudi Arabia took a calm approach, and when the United States de-secured Iran's nuclear program by signing the JCPOA, it turned to staunch opposition to Iran's nuclear program.
Four periods of Saudi Arabia's stance:

The first period (1992–2002) Positive neutrality: During this period, Iran's nuclear program was not a priority for the international community, and only the United States considered it a threat. Saudi Arabia was also mainly involved in domestic issues, reforms, and regional conflicts with Iran and did not pay attention to Iran's nuclear program. It recognized Iran's right to peaceful use of nuclear energy and expressed only environmental concerns after the Iran-Russia agreement to complete the Bushehr power plant in 1992. Saudi Arabia considered the International Atomic Energy Agency's monitoring of Iran's activities sufficient.
The second period (2002–2004) Negative neutrality: During this period, the Iranian nuclear crisis began and, after the publication of satellite images by CNN, the Iranian nuclear file entered a critical phase at the behest of the International Atomic Energy Agency. The agency confirmed Iran's secrecy and the (Persian) Gulf Cooperation Council countries, especially Saudi Arabia, expressed their political, security, and environmental concerns. The United States increased pressure and demanded a suspension of Iran's nuclear activities. Iran entered into negotiations with the European Union and accepted a voluntary suspension of enrichment. Saudi Arabia supported the European diplomatic solution and considered the US military option dangerous. The country was concerned about the military consequences and the strengthening of radical groups in Iran, and emphasized that cooperation and dialogue were better than confrontation. At the same time, Saudi Arabia focused more on developments in Iraq and paid less attention to Iran's nuclear program. Saudi Arabia was also critical of the US's dual approach towards Iran and Israel.
The third period (2005–2015) Open confrontation and opposition: From 2005 to the signing of the JCPOA (2015), important changes occurred in Iran’s nuclear file. With the election of Mahmoud Ahmadinejad in 2005, Iran adopted a more assertive nuclear policy, left the Paris Agreement, and sought cooperation with new actors beyond the three European countries. The United States referred the Iranian nuclear file to the Security Council, and it became a security file. Saudi Arabia, which had previously taken a soft approach, began to confront Iran’s nuclear program more harshly from this time on; including proposing the creation of a nuclear-weapon-free zone in the Persian Gulf and supporting sanctions against Iran. WikiLeaks documents show that Saudi Arabia, behind closed doors, called on the United States to attack Iran’s nuclear facilities. However, due to the sensitivities of Arab public opinion and support for Iran’s anti-Western policies, Saudi Arabia’s opposition remained unspoken and political and logistical support remained. Saudi-affiliated media outlets also engaged in psychological warfare against Iran’s nuclear program.
Fourth period (2015 to present) Continuation of confrontation and efforts to strike a balance: The JCPOA treaty created a significant change in the regional order that Iran’s rival countries, especially Saudi Arabia and Israel, were unhappy with. After Trump came to power and the US withdrew from the JCPOA, Saudi Arabia’s efforts to confront Iran intensified. Saudi Arabia adopted three main strategies within the framework of defensive neoclassical realism: calling for an international coalition to contain Iran, strengthening its defense and missile capabilities, and trying to acquire nuclear technology.

Saudi Arabia initially sought to prevent the development of Iran’s nuclear program by supporting the Security Council and sanctions and tried to participate in the nuclear negotiations. The JCPOA agreement, which gave Iran a stronger position, worried Saudi Arabia and caused it to resort to more extensive security and military measures, including purchasing weapons from the US and bribing Russia to prevent the sale of defense systems to Iran. Even the claim of trying to obtain nuclear weapons from Pakistan sought to balance against Iran.
Also, Saudi Arabia launched its national nuclear program to confront Iran and signed agreements for nuclear cooperation with the United States, France, and China. A plan to form an international uranium enrichment consortium was also presented by Saudi Arabia to control nuclear activities in the region, which Iran did not accept. These measures indicate Saudi Arabia's efforts to confront Iran's influence and nuclear capabilities in the region.
Conclusion
Iran and Saudi Arabia, two regional powers and rivals in the Islamic world, have complex relations that have been significantly affected by Iran's nuclear program. Initially, Saudi Arabia did not attach much importance to Iran's nuclear program, but over time, this issue became one of the important factors in the relations between the two countries. The theory of neoclassical realism shows that regional actors adopt appropriate security policies to maintain the balance of power and increase their sources of power.
Saudi Arabia, an ally of the United States, does not consider its behavior to be entirely in line with Washington's policies and has always emphasized a peaceful resolution of the Iranian nuclear issue and the creation of a Middle East free of nuclear weapons. However, since the Mahmoud Ahmadinejad administration, Saudi Arabia has taken a tougher stance against Iran's nuclear program, supporting sanctions and even considering military action. However, Saudi Arabia's willingness to pursue a military solution was limited, as this action could have provoked a strong reaction from Iran and the activation of its regional networks.
The JCPOA agreement was not accepted by Saudi Arabia, and the country tried to reduce Iran's achievements by supporting Trump's anti-Iran policies. At the same time, competition and proxy wars between the two countries continue, but recently both sides have sought to reduce tensions and protect their interests, although their relations remain sensitive and changing.