DeBlasio does not represent the United States abroad. By doing so he is violating law, 18 U.S. Code § 953, which carries a prison term of three years.
Lock him up.
You're G-d d@mn right. He CANNOT be allowed to contradict official US foreign policy, not to mention that it's illegal. DeBlasio is NOT the President. He's the barely adequate mayor of a large, out of touch, declining city.