Just 40 years ago, US president Richard Nixon arrived in Beijing for what he immodestly but accurately called 'the week that changed the world'. Knowledgeable observers knew that the success of the visit - so crucial to Nixon's 1972 re-election campaign - would turn on how he and his national security adviser, Henry Kissinger, dealt with the status of Taiwan.
That question had been central to Sino-US relations since the communist victory in the Chinese civil war and establishment of the People's Republic of China in 1949, and it continues to be so today.
For over two decades following the start of the Korean conflict in June 1950, the US denied that Taiwan was part of China. Yet that had not been its original position after the second world war. During the war, in the 1943 Cairo Declaration, the US, Britain and China had agreed that Japan, which had forced China to cede Taiwan to it in 1895, would have to return the island to China at the war's end. Thus, in October 1945, the victorious Allies authorised Chiang Kai-shek, then president of the Republic of China, to accept Japan's surrender on the island.
Chiang, without waiting for any peace treaty to formalise the island's return, reintegrated Taiwan into China's political system. By the autumn of 1949, Chiang's government, after being defeated by the forces of Mao Zedong on the mainland, had made Taiwan its last refuge against the communist revolution, and Mao was preparing an assault on the island that was to complete the revolution.
In the United States, the Truman administration, which was under severe domestic political attack from the Republican Party opposition for supposedly having 'lost China' to communism, was deliberating how to respond to demands that it prevent the impending Maoist onslaught by interposing the Seventh Fleet in the Taiwan Strait. After an agonising and acrimonious national debate, in January 1950 president Harry Truman and secretary of state Dean Acheson, in successive speeches, announced that the US would not intervene. To do so, they said, would involve the US in China's civil war and be seen as interference with the territorial integrity of an Asian state.
They based their decision on the premise that Taiwan had again become part of China, despite the fact that its new status had not yet been formally confirmed by any peace treaty. As Acheson, an able attorney, put it: nobody 'raised any lawyer's doubts' when Chiang's forces were placed in charge of Taiwan at the end of the war. That, he said, had been done in accordance with the Cairo Declaration and subsequent wartime commitments.
Yet, less than six months later, when North Korea invaded South Korea, the US interpreted the invasion as an attack by 'international communism' not only in Korea but also against Taiwan and Indochina. With no national debate, Truman immediately announced that he had ordered the Seventh Fleet to protect Formosa, using Taiwan's Western name, and, to justify their momentous decision, Truman and Acheson changed the American legal position. The president proclaimed that the legal status of the island was as yet undetermined and would have to await restoration of security in the Pacific, a formal peace treaty with Japan or consideration by the United Nations.
