One of the most striking turnarounds in the Middle East is the sudden close rapprochement between Syria and Iraq, who in their moves along the Syria-Iraqi border are increasingly coordinating together against both ISIS and the US.
To be clear, this is a major turnaround. Since the Second World War Syria and Iraq have more often been in bitter conflict with each other than allied with each other.
In the 1960s the antagonism between the two countries sharpened when they each came to be led by rival branches of the Baath party. There is nothing more calculated to intensify hostility than an ideological split as the history in the twentieth century of the world Communist movement can testify, and in the case of the hostility between the rival Baathists of Syria and Iraq the antagonism became murderous, with former Syrian President Hafez Al-Assad and former Iraqi President Saddam Hussein loathing each other.
Suffice to say that the single episode that most cemented Saddam Hussein's reputation as a psychopathic tyrant was his public round up and execution in 1979 of 68 Iraqi Baathist officials who had supported a rapprochement between Syria and Iraq. A video derived from an Iraqi television broadcast of this episode exists, and it still makes chilling viewing.
One of the consequences of the antagonism between Syria and Iraq was that the US was repeatedly able to play the two off against each other. Though Saddam Hussein has now come to be thought of as an opponent of the US, before his invasion of Kuwait in 1990 this was not really so, with Saddam Hussein repeatedly disrupting Syrian attempts to set up an Arab 'rejectionist front' to oppose the US and Israel because of his pathological hostility to Syria's Baathists.
Suffice it to say that the alliance between Syria and Iran which emerged in the 1980s - and which has held firm despite all attempts by the US, Israel and the Sunni Gulf States to break it - has its origins in the shared fear and hostility of both Syria and Iran towards Saddam Hussein's Iraq, which in the 1980s appeared to be an existential threat to both.
Following Saddam Hussein's fall the increasingly Shiite dominated governments in Iraq have tilted more closely towards Iran, and this has gradually brought Iraq closer to Iran's ally Syria. Already in 2015 this was having an effect, with Iraq agreeing to allow overflights of Russian aircraft heading to Syria across its territory.
However what was in 2015 limited cooperation between Syria and Iraq has now evolved into an outright de facto military alliance as both Syria and Iraq step up efforts to regain control of their territories occupied by ISIS whilst at the same time maneuvering to block US attempts to establish autonomous Sunni enclaves in these territories, or to play the Kurds off against both of them.
The first concrete expression of this military alliance was the Iraqi air strikes on ISIS in eastern Syria in February, which it is now known were carried out with the approval of the Syrian government. It seems that the Iraqi F16s which carried out the strike had a shorter distance to fly to reach ISIS targets in eastern Syria than the Syrian and Russian aircraft flying from their bases on Syria's western coast, making an Iraqi air strike on ISIS positions more effective than a Syrian or Russian air strike would have been.
However the most dramatic illustration of the de facto military alliance between Syria and Iraq - and the fact that it is targeted as much at blocking the regional maneuvers of the US as at defeating ISIS - is the obviously coordinated moves the Syrian and Iraqi militaries are making in order to establish joint control of the Syrian-Iraqi border.
The Moon of Alabama has explained how the sudden dash of the Syrian army to the Syrian-Iraqi border - carried out at lightning speed, with some Syrian troops apparently moving an extraordinary 180 kilometers over the course of a single day - not only took the US completely by surprise, but has negated US attempts to carve out a zone of control for itself and its proxies in eastern Syria.
A key point about this advance is however that it has clearly been coordinated with the Iraqi military, who have carried out a parallel advance towards the Syrian-Iraqi border from their side of the border. There are now reports of thousands of pro-Iraqi government militia pouring into the area to reinforce the Iraqi military's presence there.
The speed of the Syrian army's advance to the the Syrian-Iraqi border is being attributed - almost certainly correctly - to help from Russia, with claims that Russian Special Forces were directly involved in countering US moves in southern Syria. The parallel moves of the Syrian and Iraqi militaries towards the Syrian-Iraqi borders appear so obviously coordinated that it is difficult to avoid the impression that the Russians - who have excellent relations with Iraq - were involved in coordinating them.
The big question is how long this de facto alliance between Syria and Iraq will last? In the Middle East alliances tend to be transient whilst enmities unfortunately tend to be permanent. However one alliance - the one between Syria and Iran - has now held firm for over 35 years, and done so moreover under intense pressure even after the original reason for this alliance - Syria's and Iran's joint fear of Saddam Hussein - has gone.
With Iraq closely allied to Syria's ally Iran, it is at least possible that the current de facto alliance between Syria and Iraq could also evolve into something more permanent.
There has been some lurid talk in recent years of a supposedly menacing 'Shiite crescent' stretching all the way from Lebanon through Syria and Iraq to Iran.
This is a wild fantasy. The Syrian government is not Shiite but secular, and is supported by many and probably most of Syria's Sunnis. Though there are Shiite sectarians in Iraq, and though they are for the moment in the ascendant, opinion polls show that the majority of Iraqis - Sunnis and Shiites - reject religious sectarianism, and oppose attempts to divide them on religious grounds.
I would add that the supposed conflict between Shiites and Sunnis in the Middle East is anyway largely misunderstood in the West, which wrongly interprets it through the prism of early modern Europe's very different Protestant-Catholic conflict. In reality non-Salafi/Wahhabi Sunnis - who are the great majority of Sunnis - have theologically far more in common with Shia Muslims than they do with the Salafi/Wahhabi Sunni Muslims who make up the various Jihadi movements.
Though it is wrong therefore to speak of a 'Shiite crescent', it does seem that an evolving geopolitical alignment pitting Iran, Iraq, Lebanon and Syria against Israel and a group of Arab states led by Saudi Arabia may be in the process of forming.
If so then that will be a direct result of US and Saudi policy, which in the case of Syria and Iraq, by trying to weaken both, is bringing these former foes together.
The Iraqis don't want the US in their country. So in some regards, this is a good move for them, as well as Syria and Iran.