Last week's Turkish airstrikes on People's Protection Units' (YPG) positions in northern Syria and north-western Iraq followed by clashes between Turkish border guards and YPG forces have dramatically raised the stakes in the scramble to determine the political landscape of Syria's Kurdish-majority region.
Whilst at operational and tactical levels the Turkish airstrikes are clearly designed to hurt the YPG and its political ally, the Democratic Union Party (PYD), in strategic terms the strikes are a clear message to the United States.
In north-eastern Syria, the US is allied to the YPG and the PYD, both of which are extensions of the Kurdistan Workers' Party (PKK). The PKK is listed as a terrorist organisation by both the United States and the North Atlantic Treaty Organisation (NATO) as a whole.
The fact that the US is allied to the outliers of a terrorist movement speaks foremost to the complexities of the Syrian conflict and the determination of each player to control the outcome of the conflict in the north-eastern corner of Syria.
In that specific conflict at least, Turkish plans are radically different to US ones, an important divergence which throws up a range of volatile scenarios. The predictable consequences are two-fold: first, in the Syrian theatre Turkey is likely to re-align even further toward Russia and possibly even Iran. Second, in a broader strategic landscape this local Turkish-American disagreement may well extend to other arenas, thus weakening Turkey's position in the NATO alliance.
PKK in Syria
In north-eastern and north-central Syria, the areas under YPG and PYD control are often referred to as "Rojava". Whilst pro-Kurdish journalists and activists in the West present this as a beacon of democracy, economic fairness and gender equality, the truth is that "Rojava" is the embodiment of the PKK's ideology. It combines selective interpretations of Marxism, quixotic reading of globalisation and above all militant Kurdish nationalism to project a mysterious and potent ideological force.
It is not surprising that idealistic Europeans and North Americans are attracted to this ideology and travel to PYD-controlled areas ostensibly to fight Daesh.
This influx is not limited to idealistic Westerners but includes people from every corner of the globe. The intriguing story of Amir Qobadi, a non-Kurdish Iranian from Mashhad who died fighting for the YPG in Kobane, is illustrative of the depth and breadth of the PKK's ideological appeal.
From a Turkish perspective, the emergence of a Kurdish proto-state on its southern border constitutes an intolerable provocation. The strong PKK connection of the YPD ensures a cross-pollination of transnational threats, driven by ideology and ethnic irredentism. The inescapable strategic fact is that as "Rojava" strengthens in Syria so does the PKK in Turkey, with all too obvious adverse ramifications for Turkish national security.
New Turkish approach?
Last week's airstrikes represent an intensification of an existing comprehensive Turkish strategy of containing the YPG and PYD. The military dimension is well thought-out, as demonstrated by the "Euphrates Shield Operation" which has now concluded.
The apparent success of "Euphrates Shield", in so far as it met the twin goals of ejecting Daesh from important outposts in north-western Syria in addition to checking the westward advance of the YPG, creates an irresistible template for future Turkish encroachments onto Syrian territory.
The depth and duration of future interventions will depend on the strength of the threat posed by the YPG. Under extreme conditions Turkey could deploy forces on a near-permanent basis, if only to apply pressure on other key players to moderate Kurdish expectations in Syria.
But the political and diplomatic dimensions of the Turkish strategy are equally important. These rest principally on Turkey's alliance with the Iraqi Kurds, notably the Erbil-based Kurdistan Democratic Party (KDP) and the Peshmerga forces under its control. This alliance ensures that the YPG at least doesn't consolidate a presence in Iraq.
However, elements of the main PKK organisation maintain an embattled presence in the Sinjar mountains area. This was the ostensible justification for the Turkish strikes in the area last week which also inadvertently inflicted casualties on KDP-aligned Peshmerga.
In terms of the fallout with the United States, the centrality of the YPG-PKK threat to Turkish national security essentially means either Washington qualifies its support for the Syrian Kurds or it risks deeper and wider escalation with Ankara.
It is worthwhile to look at this issue from an historical lens. Turkey has been an important American ally and loyal NATO member since the early 1950s. The country's critical location at the crossroads of Europe and Asia has necessitated the formation of structural defence and security ties with Europe and America.
That said, these ties have been eroding since early 2003 when Turkey boldly refused American requests to use Turkish territory as a launch pad to invade northern Iraq. This latest spat with Washington is a demonstration of Turkish independence and strategic resolve which will inevitably impact on the country's broader relations with the Western military alliance.
The views expressed in this article belong to the author and do not necessarily reflect the editorial policy of Middle East Monitor.