 Britain 's Statute of Westminster 1931 formally ended most of the constitutional links between Australia and the UK . Australia adopted it in 1942 , but it was backdated to 1939 to confirm the validity of legislation passed by the Australian Parliament during World War II . The shock of the United Kingdom 's defeat in Asia in 1942 and the threat of Japanese invasion caused Australia to turn to the United States as a new ally and protector . Since 1951 , Australia has been a formal military ally of the US , under the ANZUS treaty . After World War II Australia encouraged immigration from Europe . Since the 1970s and following the abolition of the White Australia policy , immigration from Asia and elsewhere was also promoted . As a result , Australia 's demography , culture , and self @-@ image were transformed . The final constitutional ties between Australia and the UK were severed with the passing of the Australia Act 1986 , ending any British role in the government of the Australian States , and closing the option of judicial appeals to the Privy Council in London . In a 1999 referendum , 55 % of voters and a majority in every state rejected a proposal to become a republic with a president appointed by a two @-@ thirds vote in both Houses of the Australian Parliament . Since the election of the Whitlam Government in 1972 , there has been an increasing focus in foreign policy on ties with other Pacific Rim nations , while maintaining close ties with Australia 's traditional allies and trading partners . 
