US Foreign Policy on Iraq: Breaking the Shia Alliance in From Syria to Iran.

The US is unlikely to intervene militarily in Iraq again unless the Kurdish region were threatened or if Baghdad were to fall under an an attack by ISIS and revived Baathist forces, thus opening the way for the major oil producing regions in the south to be menaced.

For the Obama administration the threat from ISIS presents an opportunity to put pressure on Maliki not to allow Iraq to be used as either a land bridge for Iran's support for President Assad or for its air space to be used to transport weapons to Lebanon's Hizbollah.

It has been a continued aim of the foreign policy of Clinton from 2011 onwards as Secretary of State and then, as potential presidential candidate, that 'Assad must go'. Washington is concerned at the possibility that Assad has looked like stronger in Syria and that Baghdad is moving too close to Tehran.

Not only has Iraq signed a $195m arms deal with Iran, the threat of the 6,000-kilometer "Islamic Pipeline' from the South Pars gas field to the Eastern Meditteranean would become closer to realisation, thus angering Qatar with whom Iran shares the huge reserves of gas in the Gulf.

Qatar has bankrolled and funded Sunni jihadists, some in groups that are affiliated to Al Qaida, as a means of both removing Assad and furthering the rival plan to build a gas pipeline to Turkey and thence on to European markets, one reason why Britain and France have allied with Qatar.

One reason for the speed and scale of ISIS's surge from northern Syria into central Iraq, and Al Qaida's break with ISIS, is that Assad was cunning enough to have left it alone, realising it would fight against the other jihadists and tie up both the FSA and Kurdish separatists in the north.

ISIS was able to operate and spread because in 2013 Qatar was prepared to finance and arm the most fanatical jihadists such as Ahrar al-Sham and Turkey was prepared to allow ISIS to develop so as to fight alongside the FSA as a means of countering the threat of Kurdish irredentism.

Until 2014, ISIS was a staunch ally of the Free Syria Army until it became apparent that by attacking the Kurds, they were allowing Assad down south in Damascus the freedom to roll back the FSA from its positions outside the Syrian capital ( leading to accusations Assad was funding ISIS ).

In fact, the chaos and the rise of ISIS is more to do with the FSA being riven with factional struggles between those backed by Qatar and those by Saudi Arabia, both of which are vying to impose their leadership on the Sunni insurgent forces should Assad be overthrown.

Saudi Arabia has been wary that Qatar's preparedness to back the Muslim Brotherhood which is a traditional enemy and hostile to the Wahhabite state. But it has been more concerned with rivalling Qatar with Salafists that would do their bidding such as the Jabhat Al Nusra Front.

The upshot of this sordid power politics is that ISIS has grown into a major threat because of the way Syria has acted as a cockpit for backing the most ruthless Sunni jihadists so as to get rid of Assad and advance energy interests with the tacit backing of the US and Britain.

As a consequence of a shoddy realpolitik, the entire region has become even more unstable and Iraq more so than at any time since the sectarian warfare that erupted after the US invasion of 2003. ISIS is regarded by Maliki in Iraq as part of a Saudi plot; Assad is blamed by the FSA for supporting it.

Saudi Arabia clearly could have an interest in seeing Iraq descend into sectarian warfare. ISIS would engage the Shia government in Iraq and thwart Iran's plans to extend its interests westwards. The US would only intervene if the Kurdish oil fields or those in south Iraq were threatened.

Washington would be quite content to see Iran checked by having Maliki's government embroiled in a struggle against ISIS as it could then make military intervention to shore up his government conditional on moving away from Tehran and abandoning such plans as the Iran-Iraq-Syria pipeline.