Some analysts and politicians are raising fears that continued U.S. presence in Syria used to keep tabs on Iran could lead to unintended escalation and even trigger a war. In a previously unreported incident in 2017, the U.S. and Russia made an agreement regarding advance notice for use of airspace within a specific distance of each others’ troops. In one tense standoff, an unclear interpretation of the policy led to coalition headquarters giving a strike order against a vehicle transporting a port-a-potty to an outpost the U.S. had warned the Russians from servicing with supplies, against the threat of force. The Air Force officers received the command, however, refused to comply as they did not recognize it as a “lawful order that complied with the rules of engagement.” Given the complex mesh of proxy warfare in Syria, continued U.S. presence and strikes could fall into a disaster of the kind that was averted by the Air Force officials refusing to strike at an unarmed port-a-potty transport. And with the lack of legal justification specifically for use of force or deterrence against Iran (rather than purely counter-terrorism and addressed under the 2001 AUMF), such a mixup could mire the U.S. in an internal political battle at the same time a political escalation with Iran occurs.
Source: How U.S. Mission Creep in Syria and Iraq Could Trigger War With Iran – Foreign Policy