The Commonwealth of Australia and the United States enjoy a very close alliance relationship. Australia shares many cultural traditions and values with the United States and has been a treaty ally since the signing of the Australia-New Zealand-United States (ANZUS) Treaty in 1951. Australia made major contributions to the allied cause in the First and Second World Wars, and the conflicts in Korea, Vietnam, Iraq, and Afghanistan. Australia is also a close intelligence partner through the "Five Eyes" group of nations. U.S. Marines are conducting rotational deployments in northern Australia. This initiative and others demonstrate the closeness of the relationship. A traditional cornerstone of Australia's strategic outlook is the view that the United States is Australia's most important strategic partner and is a key source of stability in the Asia-Pacific region. Australian decision-makers have also believed that Australia does not have to choose between the United States and China. Some former Australian political leaders and former government officials, as well as media reports, have expressed concern about where Australia's relationship with the United States may be headed under the Trump Administration.While Australia has a complex array of international relations, its geopolitical context is to a large extent defined by its economic relationship with China and its strategic relationship with the United States. Australia's political leadership believes it can have constructive trade relations with China while maintaining its close strategic alliance relationship with the United States. However, shifts in the geostrategic dynamics of Asia are leading regional states such as Australia to hedge, increasingly with other Asian states, against the relative decline of U.S. engagement in the region. This is one interpretation of what is behind the recent strengthening of ties between Australia and Japan and between Australia and other regional powers in Asia. Australia also plays a key role in promoting regional stability in Southeast Asia and the Southwest Pacific, and has led peacekeeping efforts in the Asia-Pacific, including in Timor-Leste and the Solomon Islands.Under the former Liberal Party government of John Howard, Australia invoked the ANZUS treaty to offer assistance to the United States after the attacks of September 11, 2001, in which 22 Australians were among those killed. Australia was one of the first countries to commit troops to U.S. military operations in Afghanistan and Iraq. Terrorist attacks on Australians in Indonesia in the 2000s also led Australia to share many of the United States' concerns in the struggle against Islamist militancy in Southeast Asia and beyond. Australia is part of the global coalition to defeat the Islamic State (IS). There are continuing concerns in Australia about domestic Islamist terrorist threats, including from "lone wolf" attacks. Dozens of Australian citizens are believed to have gone to fight for the Islamic State.Australia's trade relationship with China has been a key source of economic growth. However, there is an ongoing debate in Australia on where the Australian economy is headed as the "China boom" subsides. While profits from iron ore and other mineral exports to China may slow, other emerging exports, including exports of Australian liquefied natural gas (LNG) potentially to a more diversified set of export partners may provide a continuing source of growth. Australia, which has signed free trade agreements with the United States, South Korea, Japan, and China, is a signatory of the 12-nation Trans Pacific Partnership (TPP) agreement.