The ANZUS treaty is a defennsive military alliance concluded in 1951 by Australia, New Zelaand, and the United States. The alliance was agreed upon in order to prevent either a rearming Japan or a rising communist China from threatening the Pacific nations, and the alliance was also a reaction to the past inability of the United Kingdom to defend the region from assault (such as at the Battle of Singapore). The alliance was effectively ended in 1984, when New Zealand refused nuclear vessels from the USA and elsewhere entry to its ports. In 2012, the USA and New Zealand achieved a thaw, and New Zealand became a partial member of ANZUS. However, on 15 September 2021, AUKUS was established as the successor of ANZUS, with New Zealand being excluded from the new US-UK-Australia partnership.