What do you call it when a foreign power blasts the hell out of a group you've created, trained and equipped?
There is no other word for it. Turkey is now waging a proxy war against US in Syria. It has always been clear that Turkish and American interests in Syria do not necessarily match, but until now Turkey had refrained from using its military to blast those contrary US interests to high heaven.
That's all changed now that it has emerged that Turkey is now bringing its military force to bear not only against its old enemy the Syrian Kurds, but also an allied formation that is a US creation from the get-go.
In Syria US has always had two problems. The first problem was that whichever non-jihadi "Free Syrian Army" groups it created, trained and equipped these as a rule were quickly pressured by Al Nusra to disband and their weapons and fighters incorporated into the rebel military structure controlled by Al Nusra. Try as it might – except in the south on the border with Jordan – US could not establish a meaningful Syrian rebel network of its own (and eventually "got around" the problem by simply funneling resources into the one controlled by Al Qaeda).
Secondly, in its slow motion war against ISIS it found that having shunned Assad the only forces who could possibly act as its boots on the ground were the Kurds. However, the usefulness of Kurds is limited firstly because they are not necessarily interested in dying en masse to eject ISIS from areas they can not hope to ever make part of their Syrian Kurdistan region. And secondly, because Syria's majority Sunni Arabs are not necessarily thrilled to see the Kurdish YPG take over military control of more of the country.
Thus enter the "Syrian Democratic Forces". Almost certainly midwifed into existence by the US they are a heavily YPG-dominated coalition of Kurdish and Arab militias (as well as some Assyrian, Armenian and reportedly Turkmen). The SDF upholds the "Free Syrian Army" brand, but is at the same time at war with the Al Nusra-controlled rebel mainstream. And given that the powerful YPG is a part of it, it actually has the strength to keep Al Qaeda at bay.
The SDF thus hypothetically offers the US a way out of its two major conundrums in Syria. Under Kurdish protection US-trained FSA formations can actually survive and their survival in turn makes the SDF something else than a solely Kurdish outfit thus hopefully making its gains into majority Arab-populated regions less offensive to Arab Syrians, and also the group itself more willing to bleed to capture such areas (eg Raqqah) from ISIS.
Of course, all of this is rather optimistic – it hinges on the ability of finding Arab Syrians willing to sign up for an enterprise that is intent on fighting ISIS, standing up to Al Qaeda, and proclaiming opposition to Assad all at the same time. And furthermore doing it under the patronage of Kurdish nationalist YPG which is not necessarily making itself many friends among non-Kurds in areas it holds. This is a tall order indeed, but it is what the US has opted for since October 2015.
The strategy has had some success. A number of non-Kurdish militias in north-eastern Syria have signed up for the enterprise – the major reason for this is probably because the Assad government has only a very weak presence there and can therefore not offer meaningful logistical support. However, by signing up for the SDF and flying FSA flags, the assorted anti-ISIS Arab, Assyrian and Armenian outfits can receive arms from the United States.
Meanwhile in north-western Syria a number of non-jihadi rebel groups united in the "Army of Revolutionaries" that were originally trained by the US (basically the remnants of the once much more significant non-jihadi FSA in the north) have also signed up for SDF and have been apparently playing a very useful auxiliary role in the Kurdish assault against Al Nusra (AoR's bitter enemy which had hounded it out of the mainstream rebellion) in the Azaz pocket.
So far so good – except for one little detail – Turkey is doing its utmost to stall and rebuke the SDF advance, including pounding it with artillery. So here is the situation we have: the US comes up with an idea on how to finally create a proxy army for itself in Syria that is neither ISIS, nor Nusra, nor Assad (nor overtly Kurdish nationalist) and the Turks do everything in their power to blow it the hell up.
It's clear why the Turks are doing so – SDF advances complicate their Kurdish issue and they certainly don't want the retardation of their Al Nusra proxies in Syria. Ideally they would destroy SDF as a viable US proxy army in Syria and force Washington back into putting its weight (solely) behind the Al Qaeda-controlled rebellion which they are backing themselves.
However, the fact that Turkey has different interests in Syria than the US is not new. Neither is the fact that Turkey will always put its interests above those of the US. What is new, however, is that in pursuit of its own interests Ankara is willing to wage a veritable proxy war against the US in Syria.
What is even more shocking is lack of response from the United States. Washington's foreign policy is now so confused and lethargic that Ankara will very likely be allowed to get away with bringing its military might to bear against very close US proxies.
Now it is true that Turkey does so, not to defeat the US in Syria, but merely to get it to shift its policies, however, any other self-respecting global hegemon would have been able to explain to its very junior allies that blasting its assets is not an acceptable way of going about that.
In some ways US is the most powerful empire the world has ever seen, but in others it is constantly ridden roughshod over – not by its enemies, but by its allies; Israel, Saudi Arabia, and now Turkey.