The Middle Eastern security has been trapped at the hands of non-state actors: Islamic State (IS), Hezbollah, Syrian rebels, Al-Qaeda, the Kurds, etc.for almost the past five years. These elements not only tried to challenge the status quo, but also shattered the state authorities to eliminate their territorial control. The entire theater of war has been divided between two great regional rivals: Sunni-led Saudi Arabia and Shia-led Iran. Saudi Arabia is a failing state, while the Iranians have the upper hand to counter the old conservative Arab hegemony in the region. Initially, the Iranian power was not in a position to threaten the Saudis as compared to what it is today.
The wave of Arab Spring and the relaxations of Obama administration in the Joint Comprehensive Plan of Actions (JCPOA) in 2015 on nuclear issues provided an opportunity to the Shia forces in the region to expand.Iran supported the Arab Spring with the slogan of “political Islam” and amassed Shia armies to crush the IS expansion in Iraq and Syria. The demise of Assad-led Shia regime in Syria was the common desire of the United States and Saudi Arabia, but the active Russo-Iranian alliance as a back to the Assad regime hardened the Western and Saudi agendas in the region. Historically Iraq proved to be a buffer state to stop the face to face Saudi-Iranian tensions, especially after the Iranian revolution in 1978. In fact, the accumulation of Iran-led Shia forces in Baghdad posed as a serious national security threat to Saudi Arabia. The Arab Kingdom wants a Shia-less Baghdad and would even acquiesce to a Baghdad under the Arab Shia, free from Iranian influence.
But on the other side, Iran has historic ambitions to control the land swath from Tehran to Lebanon via the high value strategic Syrian-Iraqi Tanf crossing. That is the risk that the Saudis will not capitulate to, and the more the Iranian sponsorship to the Yemenis based Houthi rebels, further deteriorated the situation in the region will be. The United States will not accede to the Iranian design to siege its core Arab Sunnis from Baghdad to Lebanon and even in Yemen. The US has succeeded in utilizing the Shia militias of Iraq to crush the IS move in the area, and now it will be in the larger interests of the US to dispose these Shia entities in the near future.
Primarily, the purges of Iran-led Shia forces from Iraq to Lebanon will automatically defuse the Saudi-led Yemeni crisis. The massive Iranian power accumulation in Iraq, Syria, and especially in Lebanon will be dealt as a direct security threat to the Israeli national security. The Iranians should understand its power limits in the region, and the direct attack from Yemen on Saudi homeland will convolute the diplomatic and conflict resolution initiatives in the region. The US will restore the regional balance of power at any cost, even though it would lose its core Sunni allies in the region. In fact, the equation of power in different poles of Middle East is in the long term interest of the US grand strategy.