The US will offer more limited support to allies, according to the Pentagon's new National Defense Strategy. In a significant shift to its security priorities, the US Department of Defense now considers security of the US homeland and Western Hemisphere - not China - as its primary concern. Previous versions of the strategy - published every four years - named the threat posed by China as the top defence priority. Relations with China will now be approached through strength, not confrontation, the report says. The defence strategy reinforces recent calls from President Donald Trump, including for greater burden-sharing from allies in countering threats posed by Russia and North Korea. The new 34-page report follows last year's publication of the US National Security Strategy, which said Europe faced civilisational collapse and did not cast Russia as a threat to the US. At the time, Moscow said the document was largely consistent with its vision. By comparison, in 2018, the Pentagon described revisionist powers, such as China and Russia, as the central challenge to US security. The new strategy calls on American allies to step up, saying partners have been content to let Washington subsidise their defence, although it denies the shift signals a US move towards isolationism. To the contrary, it means a focused and genuinely strategic approach to the threats our nation faces, it says. Washington has long neglected the concrete interests of Americans, the report says, adding the US does not want to conflate American interests with those of the rest of the world – that a threat to a person halfway around the world is the same as to an American. Instead, it says allies, especially Europe, will take the lead against threats that are less severe for us but more so for them. Russia, which launched a full-scale invasion of Ukraine nearly four years ago, is described as a persistent but manageable threat to NATO's eastern members. Unlike in previous versions of the strategy, Taiwan, the self-governing island claimed by China, is not mentioned. However, the document does write that the US aims to prevent anyone, including China, from being able to dominate us or our allies. Late last year, the US announced a vast arms sale to Taiwan worth $11bn (£8.2bn), leading China to hold military drills around the island in response. The strategy also outlines a more limited role for US deterrence of North Korea. South Korea is capable of taking primary responsibility for the task, it adds.