When Russia and Iran foiled our regime change plans in Syria, we went to Plan B - partition of Syria.
Vital to this plan were the Syrian Kurds. Vital to the Syrian Kurds was the SDF - an umbrella group that includes both Kurds and Syrian Arabs. Because in order to partition Syria, the SDF needed to occupy the oil-rich Deir Ezzor region, and the population of Deir Ezzor is Arab, not Kurd.
The Saudi/U.S. plan is to starve the Syrian government of it's own oil via a military embargo.
This part of the plan is in effect.

Which brings us to the problem.

Tribes in the east of Syria have refused to cooperate with alleged Saudi Arabian, Kurdish and US plans to create a breakaway state east of the Euphrates River, Arabic-language news site Al-Ahd has reported.

According to reports, the Saudi Minister for Arab Gulf Affairs, Thamer Al-Sabhan, yesterday visited eastern Syria, which is currently under the control of the Syrian Democratic Forces (SDF), the Kurdish-led Syrian opposition group comprising a mix of ethnic groups.

Al-Sabhan’s goal was reportedly to influence the tribes inhabiting the area to join a vague deal allegedly agreed upon by Saudi Arabia, the Kurds and the US to separate the region east of the Euphrates River from the rest of Syria.

Most of the Arab tribes in the region, however, are fiercely opposed to such a plan and sympathise with the regime of Syrian President Bashar Al-Assad for the sake of a “unified Syria”.

The leader of the Al-Mashahada tribe in Deir Ez-Zour province, Sheikh Haider Al-Hammadi, stated that “all the Syrian tribes, except for the Al-Sharatham, refuse to visit Al-Sabhan and assist them in the blatant interference in our national affairs”.

Hammadi also accused Al-Sabhan – who was accompanied by US officials – of attempting to “[use] funds and the distribution of money” to influence their decision, but said that this “will not change the reality that [Al-Assad] has the loyalty of most Arab tribes”.

This definitely has a dirty, unseemly appearance to it. Although not as unseemly as CIA military aid to al-Qaeda in Syria, which was happening for much of the Obama Administration.
With Syrian Arabs refusing to participate in this charade, the Syrian Kurds have cracked down.

The Syrian Elite Forces (SEF) were meant to be a multi-tribe, moderate Arab armed group that would be instrumental in taking back their home province of Deir ez-Zor from the Islamic State (IS). It did not, however, end up that way.
...Some now claim to be paying dearly for this.

Over several days in late May 2019, Al-Monitor spoke to former and current members of the SEF and was repeatedly told that the SDF had targeted those that refused to join with arbitrary arrests, “confiscation” of cars and weapons, and other abuses of power.

This is not a stable situation. The Kurds cannot militarily occupy the Deir Ezzzor region long-term without the consent of the local Arab population, and things are getting worse.
This is a tinderbox that could catch fire any day now and spoil our plans for Syria.