Bilateral relations between Turkey and Iran have been marked by relative peace and stability for the past four centuries. Since the founding of the modern Republic of Turkey in 1923 and the creation of an absolutist monarchy in Iran in 1925, the ruling regimes of both countries have sought to consolidate their domestic power and to pursue an independent foreign policy. Neither Turkey nor Iran has viewed one another as an immediate threat to the attainment of these vital objectives.
During the Cold War, fearing Soviet expansionism and Soviet influence in their domestic affairs, Turkey and Iran aligned with the pro-Western camp. As founding members of the Central Treaty Organization (CENTO), Turkey and Iran became regional allies. The United States supported their efforts to cooperate bilaterally and multilaterally. In 1964 Iran and Turkey, along with Pakistan, founded the Regional Cooperation and Development Organization to promote economic, technical, and cultural cooperation among the members. Turkey perceived Iran as a status quo power, and thus non-threatening to its security or position in the region.
The 1979 Islamic Revolution shook the stability of Turkish-Iranian relations. The Islamic Republic of Iran’s militant Islamist statements and foreign policy fuelled tension and mutual distrust. However, both countries sought to prevent conflict or a rupture in relations. This reluctance to escalate the tensions stemmed largely from their desire to protect their economic interests, given that Turkey was an exporter of goods to Iran and Iran was a major energy supplier for Turkey.
The end of the Cold War paved the way for a rivalry to emerge between Turkey and Iran in Central Asia and the Caucasus. With the disintegration of the Soviet Union in 1991, Iran and Turkey sought to increase their influence and power in the newly independent former Soviet republics. Both countries underlined their common history, values, and linguistic and religious affinities with the peoples of Central Asia and the Caucasus. Western countries, especially the United States, which feared the spread of political Islam in the area and regarded Turkey as a “model” to the former Soviet republics, supported Ankara’s efforts.
The improvement of Turkish-Israeli relations has been a source of tension between Iran and Turkey. Having recognized the State of Israel in 1949, Turkey always has been cautious in its relations with Israel in order to avoid offending its Arab neighbors. However, the advent of the Madrid peace process between the Arab states and Israel paved the way for improved relations between Turkey and Israel. When both countries signed a comprehensive defense and security cooperation agreement in 1996, Iranian officials expressed their suspicions regarding such an arrangement and voiced their opposition. This development pushed Iran to align with Iraq and Syria in order to balance the Turkish-Israeli military alliance.
The 1990s also have witnessed a deterioration in Turkish-Iranian relations, especially due to the threat perceptions of these countries with respect to their domestic security. Turkish secularists and the military were suspicious of Iran’s intentions. Turkey accused Iran of interfering in its domestic affairs by supporting radical Islamic organizations propagating against the secular regime in Turkey. The events reached a peak on the night of February 1, 1997, when during the commemoration of the “Jerusalem Day” in Sincan (a small town in the environs of the Turkish capital of Ankara), posters of Hizbullah and Hamas were displayed and the participants strongly criticized the secular regime of the Turkish Republic. One of the participants, then-Iranian Ambassador to Turkey Mohammed Reza Bagheri, reportedly called for the institution of Shari‘a in Turkey 
The Sincan incident alone shows how closely Iran’s activities in Turkey were being monitored and how promptly and effectively the secular circles within the state structure confronted them. Hence, following the revelations in August 2002 by an Iranian opposition group of Iran’s secret uranium enrichment and heavy water production facilities, which are clear indications of Iran’s long-term nuclear ambitions, Turkey would be expected to have raised much more serious concerns about Iran’s efforts to become a nuclear power.
Nevertheless, in the post-September 11 period, Turkey adopted a substantially different attitude toward Iran. Following the events leading up to the US invasion of Iraq in 2003, the relationship between Turkey and Iran seemingly has entered a new phase. Similar concerns about the probable consequences of developments in Iraq have caused the two countries’ positions with respect to regional political issues to converge.
Turkey’s official stance toward Iran’s nuclear program is clear. Turkey recognizes the right of Iran, which is a member of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), to develop nuclear technology, provided that it remains on a peaceful track and allows for the application of full-scope safeguards inspections by the International Atomic Energy Agency (IAEA) in such a way that would lend the utmost confidence to the international community about its intentions.
The consensus view among the Turkish political and security elite is that, contrary to its apparent low-profile stance, Turkey cannot stay aloof from Iran’s nuclearization for long. The presence of nuclear weapons in the Iranian military arsenal will upset the delicate balance that exists between the two nations since the Kasr-i Shirin Treaty in favor of Iran.
Considering the fact that Turkey is a member of the United Nations Security Council for the period of 2009 to 2010 as well as a newly elected member of the Board of Governors of the IAEA, where Iran’s nuclear program will continue to be the top agenda item, the nature as well as the extent of Iran’s nuclear program is highly likely to have a decisive impact on the future of Turkish-Iranian relations.
Bearing in mind the rivalry between the Turks and the Iranians throughout history, despite the fact that some common concerns exist as regards their national interests, the scope and the content of Turkish-Iranian relations may not go far beyond the present levels unless Turkey makes a radical turn in its relations with the West in general, and with the United States in particular, even if they may not be at satisfactory levels either.
. John Calabrese, “Turkey and Iran: Limits of a Stable Relationship,” British Journal of Middle Eastern Studies, Vol. 25, No. 1 (1998), pp. 75-94.
. Hakan Yavuz, “Turkish Israeli Relations through the Lens of the Turkish Identity Debate,” Journal of Palestine Studies, Vol. 27, No. 1 (1997), pp. 22-37.
. Mustafa Kibaroglu, “Turkey and Israel Strategize,” Middle East Quarterly, Vol. 9, No. 1 (Winter 2002), pp. 61-65.
. Calabrese, “Turkey and Iran,” p. 85.
. Yavuz, “Turkish Israeli Relations through the Lens of the Turkish Identity Debate.”
. Mustafa Kibaroglu and Baris Caglar “Implications of a Nuclear Iran for Turkey,” Middle East Policy, Vol. 15, No. 4 (2008).
. Tarik Oguzlu and Mustafa Kibaroglu, “Incompatibilities in Turkish and European Security Cultures Diminish Turkey’s Prospects for EU Membership,” Middle Eastern Studies, Vol. 44, No. 6 (2008), pp. 945-962; Mustafa Kibaroglu and Tarik Oguzlu, “Turkey and the United States in the 21st Century: Friends or Foes?” Korean Journal of Defense Analysis, Vol. 20, No. 4 (2008), pp. 357-372.
"The 1979 Islamic Revolution shook the stability of Turkish-Iranian relations."