Islamic Republic of Iran is faced closely with records like the numerous neighbors, the diversity of geopolitics, ethnic and linguistic heterogeneous countries, maximum production, the drug trade as well as the terrorist actions in its surrounding environment. In the meantime, Iraq is a country that is also considered part of the Arabic Middle East geopolitical area, on the one hand, and the most heterogeneous country, ethnic and language, on the other hand. Aggressive actions of former Iraqi officials, political instability, the creation of a favorable and appropriate environment for the emergence and activity of Takfiri groups are the factors challenging and threatening Iran's national security. Although democratic Iraq – with Shiite majority in power structures-is a good choice for Iran's national security, challenging the option in terms of geopolitical strategy would lead to three scenarios: 1. powerful Iraq with a dictator leadership 2. decomposed Iraq with a power vacuum, and 3. Iraq federalism with Shiites, Kurds and Sunnis as the main actors. This study seeks to find that which of the three aforementioned scenarios would bring about the least challenge and the greatest opportunity for the Iranian national security? The findings suggest that scenario number 3 enjoys this potential.