The heads of state have gone home. For one week every September, New York fills with delegations from governments that spend the other 51 weeks collecting in the city. Then the motorcades leave, and the city goes back to running its own foreign policy.

New York has an Office for International Affairs. Los Angeles, Chicago, and Houston have some version of the same thing. These offices arrange meetings with consulates and United Nations missions, sign memorandums with foreign cities, and host visiting officials. What they do not have is the security architecture that surrounds the same work at the federal level: vetted personnel, clearances where the job requires them, and a channel for deconflicting sensitive foreign contacts with Washington.