It's a term that encapsulates the mess that awaited the US-led counter ISIS campaign when finally it wound down . The SDF -- as it was always clumsily known -- never really existed.

At its inception, the Pentagon needed a force on the ground to fight ISIS . They tried for years to find disciplined, Sunni Arab fighters, but failed repeatedly.

The Syrian Kurds, however, were both disciplined and pragmatic. But they could not be harnessed as a purely Kurdish force, plowing into Sunni Arab areas held by ISIS. So a fig leaf was created -- a new name for the Syrian Kurdish fighting units, normally called the Kurdish People's Protection Units, or YPG.

So the SDF was born, with the exaggerated claim that there were many Arabs in their ranks, and the omission of Turkish Kurds -- the PKK, proscribed by Turkey -- fighting there too. The need for a fudge was a tell that the urgent anti-ISIS campaign would end up with some problems.

Fast forward four years, and now the SDF means something entirely different. It's an acronym that spells betrayal.

Reflecting how little the Trump administration cared for the details as it rushed to clean up its self-inflicted mess, Vice President Mike Pence mistakenly referred to the SDF as the "Syrian Defence Forces" several times as he announced a ceasefire that further betrayed them. And, earlier, President Donald Trump blurted out the poorly-kept secret that the PKK were in their ranks

America's imperfect pact with the Kurds was always going to fall apart one day. But nobody could have imagined the SDF's 10,000-plus dead sons and daughters would have been betrayed by overwhelming ignorance, fealty to Turkish and Russian interests, and the toxic aversion to details that the Trump administration displayed.

The window for Russian dominance in Syria was jammed open by the pitfalls of the US-brokered ceasefire. No deal works on a battlefield if the area covered by it isn't agreed upon. Turkey thought it got all the areas it wanted on the border. The Syrian Kurds thought they had to stop shooting and let Turkey keep the ground it already had -- the latter something it had little say over militarily.

It was the perfect scene-setter for Russia to step in. Russian President Vladimir Putin's Sochi deal with his Turkish counterpart, Recep Tayyip Erdogan , took in the military reality on the ground. Turkey likely didn't want urban warfare in four to five cities on its border for months to come. To that, Putin added the Syrian regime with Russia at its back -- the keepers of an ugly peace.

Russian President Vladimir Putin meets with his Turkish counterpart Recep Tayyip Erdogan in Sochi.

There are three gaping holes in this pact too.

Firstly, the Syrian Kurds are not Damascus' evergreen friend. The Syrian Kurds spent four years in bed with the regime's enemy, the US, and there are many who fear both repression by the regime, and the conscription into the regime's army.

Secondly, the ceasefire deal allows Turkey to keep their forces right up to the M4 -- a highway in northern Syria that runs parallel to the Turkish border -- without any buffer onto the Syrian Kurdish areas that directly abut it. This could lead to further clashes and Turkish expansion.

Thirdly, a lot of Syrian Kurds live in the northern cities of Qamishli, which is exempt from the deal, and Kobani, which is right on the border and saw more Russian forces enter it Wednesday. Ensuring that no YPG or SDF fighters remain in the wide 30km area along the border is a tough task, given these men and women can return to civilian lives at night, and will frankly want to help protect their families in these areas.

So the Sochi deal is likely another pause in the fighting, rather than a permanent fix.

Moscow is unlikely to be too fussed. Their key goal is becoming the new power in the region, and this settlement, almost directly replacing US forces with their own police and political clout, does that.

The Syrian Kurds will end up in a war of attrition with the pro-Turkish rebels that populate new areas President Erdogan has seized. Damascus will likely be fine with that, as it will aid their goal of returning full regime sovereignty to Syria.

And the Kurds should be ready to be sold out again -- as this life raft demands they put their possessions on board first.

There was always some inevitability to the alliance between Syrian Kurds and the regime. So isn't this just the US doing what it had to do, but at a faster pace, as Trump likes to suggest? No. As the US mission is now left with the worst of all worlds.

An SDF fighter stands guard as the US military pulls out of northern Syria.

US troops know their commander in chief simply doesn't want them here. It seems his elliptical comment about securing oil in Syria was a nod to the couple hundred troops his military advisers convinced him to keep in the east. The oil fields -- which they will "protect from ISIS" -- are strategically useless to the US for hydrocarbons (it's not 1997 any more). But a presence there allows special forces to restrain Iranian movement in the region, still go after a resurgent ISIS, and be near ISIS detainees. The remainder of the forces must manage a precarious existence in Iraq, who repeatedly say they expect them to leave.

In short, elite troops must still go after ISIS and keep Iran in check, from a much worse geographical position than before, in territory more home to Syrian Sunni Arabs. Plus, regime and Russian forces are now calling the shots with -- and depriving them of -- their angry former Kurdish allies.

Even the US special forces withdrawal was complicated by their commander in chief. You can't claim you want to keep troops safe when you broadcast their extraction before they can implement it. Still, even at their nastiest, the Syrian Kurds could only manage to throw potatoes. Trump is their real enemy here.

The commander in chief's impulses are the outstanding mystery as this bloody Jacobean drama of treachery and gore unfolds. Why so fast? If he wanted US troops out of harm's way, why not a managed departure? Did he not understand what he was doing? Did he think Russia would do a better job of it all? Did he just like the drama of it all?

We may never know this answer, but one fact must rest heavy on Pentagon and NATO officials in this new world.

Remember, NATO was formed to keep Russia's former Soviet empire in check. Now, Russian military police have unrestrained access to hundreds of kilometers of NATO's southern border, at the invitation of a NATO member.

That is something Vladimir Putin can only have dreamed of.