Iran has been heavily involved in Iraq since the overthrow of the Saddam Hussein regime. In recent years, after the US withdrawal of combat forces, its surrogate troops have been the backbone of resistance to ISIS and Kurdish separatists. It's been widely assumed that Iran would seek to dominate Iraq once the conflict was over: but, now that it's visibly drawing to a close, another dimension is entering the picture. Strategy Page reports:
With ISIL no longer a major threat Iraq has surprised Iran (and many others outside the Arab world) by rebuilding relations with Sunni Arab neighbors and telling Iran to back off with any plans it had to dominate Iraqi politics. Senior Shia Arab religious and political leaders have been leaning this way for a long time and Iran thought the war against ISIL was an opportunity to weaken the traditional Shia Arab distrust of Iran. That did not work.
Since 2005, when accurate opinion polls and generally free elections were once again available it became obvious that both in Sunni Arab areas (where there used to be a lot of support for al Qaeda) and Shia areas (where there used to be a lot of support for the kind of religious dictatorship found in Shia Iran) that Iran was seen as the enemy. This was obvious to familiar with Iraqi history. Fear of Indo-European Iran has always been greater than the fact that most Iraqis share their Shia faith with Iranians. Blood is thicker than religion. This is why more there was always so much violence along the ethnic border between Kurds (who are ethnically related to the Iranians) and Arabs, especially in oil rich Kirkuk.
From 2005 on it became increasingly clear that the vast majority of Iraqis, including Kurds and most Shia Arabs, feared increasing Iranian influence. Although most Iraqis are Shia, they are also Arab, and do not want to be ruled by their fellow Shia in Iran. That's because the Iranians are Indo-European people and have long treated their Arab neighbors with disdain and cruelty. Iraqis could now see this happening regularly in western Iran, where the Iranian Arab minority (about two percent of the population) is constantly being persecuted by the Indo-European Iranians. The Iranian Arabs also get it from the Azeri Turk minority (25 percent of all Iranians). Iraqis have bitter memories of centuries of domination by the Ottoman Turks (who now control only Turkey), whose empire once stretched into North Africa and the Balkans.
One reason Saddam Hussein had some support from all groups in Iraq and from his Arab neighbors was his ability to keep the Iranians out. After Saddam was overthrown in 2003 many Iraqis (and most Arabs) feared that, without a badass like Saddam, there would be no one to motivate Iraqis into blocking Iranian moves to occupy Iraq, or control its rulers. But now the Shia Arab Iraqi leaders (political and religious) appear confident that they can stand up to the Iranian threats. The is one thing all Iraqis can unite behind and apparently one of many reasons why Iraq is openly demanding that Iran back off while just as publically establishing economic, political and military links with Saudi Arabia and other Sunni Arab states in the region to oppose Iranian plans for expansion and domination of Arabia.
The new alignment means more technical and economic aid from the Sunni Arab states to the south and more vigorous efforts by those Sunni Arab rulers to ensure their Shia Arab minorities (or, in the case of Bahrain, majority) are treated well and that there is little support for Sunni Arab Iraqis. The Saudi leaders had always tried to maintain good relationships with their Shia minority but that had become more difficult as radical Sunni Islam (as in al Qaeda and ISIL) became more popular. Now that form of religious zeal has become less popular in Arabia, at least for a while. But that’s another problem that is less pressing hat the immediate ones posed by Iran.
There's more at the link. Interesting reading.
I'll be watching this with great interest. Basically, Iran's surface link to Syria (where the Assad government only exists because of the military assistance, in equipment and personnel, supplied by Iran) runs through Iraq. Iran cannot afford to have that link cut, because air and sea resupply could not replace the land route. Air shipping is much more expensive, and sea transport must go through the Red Sea, where it's vulnerable to search and seizure by Saudi Arabia, and then the Suez Canal, where it's vulnerable to search and seizure by Egypt.
Iran simply cannot afford to have Iraq become too independent, thereby threatening the former's regional hegemony. Will this lead to a putsch attempt in Iraq, as Iran tries to install its supporters in power? Will the people of Iraq permit and/or tolerate that? More to the point, will Saudi Arabia and its Gulf allies permit it? If they don't, how will they intervene to stop it?
This could become 'curiouser and curiouser', as Alice famously said . . . and very bloody.