The Causes of Iran's Strategic Relations Expansion with Syria from U.S. invasion of Iraq until the start of Syrian crisis (2003 -2011)

The strategic alliance between Iran and Syria is considered as one of the longstanding regional alliances. However a very important point in the strategic relationship between the two countries is the tendency of Iran toward deepening its strategic relationship with Syria from 2003 to 2011; which started from U.S. invasion of Iraq until the outbreak of uprising in Syria in March 2011. This paper tries to answer this question: By comparison to 1979- 2003 period, why Iran was more determined to deepen its strategic ties to Syria from 2003 to 2011? Findings show that, systemic pressures including U.S unilateralism in the international system, occupation of Iraq by the U.S. in 2003 and Iran's nuclear issue have been essential variables in pushing Iran toward expansion of strategic ties with Syria from 2003 to 2011. However, these pressures and threats are interpreted through unit-level variables, especially the perceptions of elites from the international system in this period. The research methodology is descriptive-analytic based on qualitative method.