The former commander of U.S. Central Command warned Sunday that American forces were “vulnerable” to an attack by Iran or its proxies, one day after the unprecedented Iranian missile and drone barrage against Israel. “Our forces distributed across Iraq and Syria, supporting the Armed Forces of Iraq and anti-ISIS operations and supporting our SDF [Syrian Democratic Forces] partners in eastern Syria—those forces are vulnerable to an Iranian or an Iranian proxy attack,” retired Marine Corps Gen. Frank McKenzie said on CBS’ “Face the Nation.” “We recognize that. I think that’s why the president’s …