The US is leaving Syria, but maybe not all of Syria. Sources told Foreign Policy that the US was considering maintaining a presence at a forlorn desert garrison in Syria near the Jordanian border.In mid-December US President Donald Trump announced that forces would be withdrawn from Syria. “But given the garrison’s strategic importance, sources said the US government is considering a plan to keep at least some forces there.” The base currently has a 55 kilometer “exclusion zone” around it that Iranian, pro-Syrian regime and Syrian armed forces are expected to keep away from. Over the years since 2016 when the base was established there have been attempts by pro-Syrian regime forces to probe the bases defenses. The US initially established the base to train Syrian rebel fighters to fight ISIS. Hundreds of rebels were based there. However once ISIS. Was defeated in the vicinity and the Syrian regime retook areas around the base, it became unclear what the mission was in Tanf. In October last year US General Joseph Votel visited the base and appeared to showcase its importance. Meanwhile Pentagon inspector general reports indicated that Tanf was increasingly the site of tensions with the Syrian regime and Iran. US officials wondered if there was a legal mandate to keep forces in Syria to confront Iran, a strategy that had been spelled out by National Security Advisor John Bolton and hinted at by others. US officials said that the anti-ISIS mission in Syria, which had been most effective in eastern Syria, could expand to include staying in Syria until Iranian-commanded forces left.This was part of US-Israel discussions about the US role in Syria. Reports indicated that Iran was carving out a corridor of influence via Iraq and Syria to Hezbollah in Lebanon. Israel said it had struck Iranian targets in Syria in 2018, eventually admitting to more than 1,000 airstrikes. But Trump’s withdrawal was met with skepticism. John Bolton travelled to Israel in January to reassure Jerusalem of US support regarding Iran’s threats in Syria. According to a Bloomberg report, Bolton indicated that there would be no “rush to remove troops from Al-Tanf.”The lonely garrison at Tanf now may have a longer lease. Established to fight ISIS and train Syrian rebel fighters, it has now morphed into a new mission. However this raises questions about whether the assets in Tanf know that this is their mission and whether this open ended mission will be met with approval in Washington. It also raises questions about whether Tanf actually does interdict Iran’s “road to the sea” or whether it is primarily just a lonely desert base with an unclear role. It also raises questions about what will become of the tens of thousands of displaced Syrians at the Rukban camp near Tanf and Jordan’s role in maintaining a US supply line to Tanf.