It's already been established the U.S. and Western allies collaborate with ISIS and their alliances.
The paper:
https://www.lrb.co.uk/the-paper/v36/n08/seymour-m.-hersh/the-red-line-and-the-rat-line
The policy document you shared reiterates the “possibility of establishing a declared or undeclared Salafist principality”, the Pentagon report goes on, “this is exactly what the supporting powers to the opposition want, in order to isolate the Syrian regime, which is considered the strategic depth of the Shia expansion (Iraq and Iran).”
The report isn’t a policy document. It’s heavily redacted and there are ambiguities in the language. But the implications are clear enough. A year into the Syrian rebellion, the US and its allies weren’t only supporting and arming an opposition they knew to be dominated by extreme sectarian groups, they were prepared to help maintain the creation of some sort of “Islamic state”, despite the “grave danger” to Iraq’s unity, as a Sunni buffer to weaken the Syrian regime.
There was no al-Qaida in Iraq until the US and Britain invaded. And the US has certainly exploited the existence of ISIS against other forces in the region as part of a wider drive to maintain western control, especially for land grab and oil.
Also, there are links that have been well documented, with reports surfacing of oil purchases from the Islamic State [i.e., Daesh], which the Israeli government headed by Netanyahu has done.
Seymour Hersh was and remains the sole claim of material support taking place though. His credentials are very solid but it's rather odd that literally no other reporter has done a confirmation.
Generally it's a bad idea to rely on a single source.
Wikileaks' releases don't establish anything of that sort either, besides Turkey and the CIA lying about general CIA activity in Turkey. That involved the use of Turkey as a flight stop for flights containing CIA detainees.
Given the GOP's Benghazi investigations, it's extremely unlikely they would not have exploited this information against Obama. The particular claims were denied under oath.
The blowback would've entirely been on Obama's administration.
Again, there is no question that the US, Turkey and unspecified Western/Gulf nations
supported the anti-Assad forces in Syria. Some of those forces were known by said countries to consist of terrorist groups such as Al Qaeda and ISI, which resulted in the formation of ISIS.
There is also no question that the US has a history of both indirectly and directly (Iran-Contra, ...) supporting militias/terrorist groups to further geopolitical goals. As the documents I referred to show, the aforementioned list of nations absolutely exploited the various terrorist groups operating in Syria to further their goal of getting rid of Assad.
If anything, the best case for material support is the UK trial of Bherlin Gildo, who was tried for terrorism offenses relating to his activities as a member of Al Qaeda. When the defense requested any records from MI6 relating to support (both material and non-material) of Al Qaeda in Syria, the prosecution ended up dropping the case entirely.
MI6 did not want to hand over anything to the prosecution, resulting in the case being dropped after the prosecution stated a "conviction was no longer likely" after a "full review of the case."
Gildo was later successfully prosecuted in Sweden for charges relating to his Al Qaeda membership.
This case seems much more substantial to support the argument of material support (at least when it comes to MI6) than the article's claims that have remained single-sourced to this day. That being said, it is not that entirely unusual that highly classified intelligence records have tanked a case.
As far Israel buying ISIS oil, I'm aware of those reports but I would add somewhat of a distinction. ISIS' main income came from trafficking oil, because obviously no one wants to be buying oil from ISIS. Through middlemen, they trafficked oil to various nearby countries such as Turkey and Kurdistan. Even the paper that originally unearthed this notes that through middlemen, ISIS oil was rebarreled and sold to a wide variety of knowing and unknowing vendors. Israel bought a lot of its oil from Kurdistan, which was prime trafficking grounds for ISIS.
Given Israel's intelligence services, I think it's reasonable to argue Israel might or should have known, or at least had reasonable grounds to assume sourcing oil from a country home to ISIS' main oil trafficking operation is likely to result in buying oil that was originally sourced from ISIS.
Ironically,
ISIS issued a statement denying they've ever sold oil to Israel but for obvious reasons we can discount that.
Also, there is a very obvious disconnect between that prior support and the idea of supporting ISIS in current times, much less directly.
