The Solomon Islands joined the UN on 19 September 1978 and belongs to ESCAP, FAO, IBRD, ICAO, IDA, IFAD, IFC, ILO, IMF, UNCTAD, UPU, and WHO. It participates in the Asian Development Bank, Commonwealth of Nations, G-77, and South Pacific Commission and Forum. The nation is a member of the WTO and a signatory of the Law of the Sea. In December 1997, Solomon Islands achieved full membership in UNESCO. The Solomon Islands has resident diplomatic representation only at the UN; the UN ambassador is also accredited to the US. The minister for foreign affairs serves as a roving envoy. The United Kingdom, Australia, New Zealand, Japan, China, and Papua New Guinea maintain diplomatic missions in Honiara; US interests are handled by its ambassador to Papua New Guinea.