Mail entering the United States from abroad arrives first at the Postal Service. The Postal Service then sends packages to U.S. Customs for examination and assessment of any duties and taxes owed. Customs processing is required for all parcels, including those sent from overseas military postal facilities (APOs and FPOs). The Postal Service is working closely with the UPU, IPC, and U.S. Customs and Border Protection to streamline and improve these processes. The Postal Service is also supporting the introduction of advance manifesting requirements for mail shipments to improve security, deter criminal activity, and enhance the efficiency and speed of clearance operations.