In another excellent article, Jonathan Spyer analyses the current status of the situation in eastern Syria (https://www.jpost.com/Opinion/The-future-of-eastern-Syria-and-the-Israeli-interest-564973?utm_source=middle+east+forum&utm_term=). To summarize, he contends that the civil war between the regime of Pres. Assad, supported by Iran and Russia, is almost over and the mainly Sunni insurgency has been defeated. This leaves Assad in control of ca. 60% of Syria, with the Kurdish fighters with US support in control of ca. 30% in eastern Syria, what was formerly IS territory, and another 10% in the north being the former Kurdish enclave of Afrin, now controlled by the Turkish Army.
This leaves Syria in a perilous state, with its future dependent not on its government or people, but rather on the policies and actions of 4 international actors, Russia, Turkey, Iran and the USA. The Kurdish-controlled region known as the “Democratic Federation of Northern Syria” controlled by the Kurdish-led Syrian Democratic Forces (SDF) is able to survive only because of US-support and the presence of a US air base at Al-Tanf and several hundred US special forces. What is most significant is that this region stands right in the path of Iran controlling a Shia crescent from the Iranian border thru Shia-controlled Iraq and pro-Shia Assad-controlled Syria thru Shia Hezbollah-controlled Lebanon to the Mediterranean Sea, which has always been the aim of the Khomeini Shia revolution since 1979.
This actually puts the US in a strong position, since it controls this significant piece of real estate, 30% of Syria, that blocks Iranian ambitions of expansion. Further, it gives the US a say in the outcome and fate of Syria, which will have to be reached by negotiation between the parties, or it will lead to another war. Pres. Trump has gone on record as saying he wants to withdraw US forces from Syria, but that would be a mistake of historic proportions, akin to Pres. Obama’s colossal error in allowing Russia into Syria in the first place (with his so-called red-line). Such a US withdrawal would create a power vacuum in eastern Syria that would be filled by Iran and would enable them to directly supply weapons to Syria and Hezbollah and would exclude the US from any say in the fate of Syria. It is in Israel’s interest to have the US in eastern Syria, more even than its attempt to control the Golan Heights adjacent to Israel, since this would be a major factor in blocking Iran’s path to achieve its aim of attacking Israel.