This caused many of the US’s regional partners to panic that they would be left alone to fight ISIS and the Iranian Regime, while the mullahs took the opportunity to increase its military shipments to Damascus, causing Iraq to retreat and Turkey to make concessions to Iran. The fallout became so bad that US Defense Secretary Jim Matthis resigned in protest and Trump was forced to slow down the withdrawal of troops.

After all, while the battle is in Syria, the real war in the Middle East is against the Iranian Regime’s attempts to take over the region. The mullahs already claim to control Yemen, Syria, Lebanon and Iraq, from where they threaten Jordan, Israel, and other US partners.
In reality, the US cannot pull out of Syria, without changing its policy on Iran, which is currently to put “maximum pressure” on the Regime to end its malign behaviour in the region. The simple truth is that, despite promises by Bashar Assad, the Syrian regime cannot evict Iran

Yes, Syria promises that Iran will leave by 2021 and they may even formally request that Iran leaves by then. But the promise is worthless because Iran only acts according to what will keep the mullahs in power the longest.

Abdulrahman al-Rashed, the former General Manager of Al Arabiya News Channel, wrote: “Iran’s military presence in Syria is a pivotal threat to the region. If Tehran ever exits Syria, its influence on the Baghdad government would diminish and political balance in Lebanon would return. And if Khamenei’s influence in Syria ends, his influence would also weaken within Tehran. Despite all the promises, Damascus will not be able to distance itself from Iran; neither today nor in 10 years from now, except through military confrontation and exerting pressure on it in more than one area.”

The Regime and their proxy forces will remain in Syria until they decide it is no longer helpful to them, so the US cannot leave Syria as they will only become a vassal state for the Iranian Regime and liable to another conflict in the coming years.