Global megatrends are coming for the ANZUS alliance

Australians are remarkably steadfast supporters of our alliance with the US. This year's Lowy Institute poll shows that 78 per cent of Australians think the alliance is either fairly important or very important. Over the 16 years the institute has been asking that question, the average is 77 per cent. Only once, in 2007, was the number below 70 per cent.

Australians may oppose US policy from time to time, and the poll shows that we are not always enthusiastic about supporting the US when it goes to war. Australians also clearly prefer some US presidents over others. Still, this is an incredibly consistent result. What explains it?

Clearly the long historical bond with the US counts for a lot, as do our shared political traditions. The other big factor is that our political leaders have been so consistently supportive of the alliance. In fact, the alliance has become closer over the course of this century. First John Howard struck up a close personal and policy bond with George W. Bush after the 9/11 attacks, then subsequent prime ministers from both major parties continued to draw closer to Washington. We now even host US marines in Darwin.

It tends to get overlooked, but the bond with America is deep in the DNA of both our major parties. So important is the alliance to Labor and the Liberals that they both claim authorship of it. For the Liberals, the alliance was an expression of the anti-communism that defined the party from its earliest days. For Labor, the fit with America was less easy; there was always a suggestion of antipathy or distrust until the 1980s, when the unambiguously pro-American Bob Hawke became prime minister.

All in all, we can say that the alliance is deeply ingrained in our history, our public opinion, and our politics. That's an incredibly solid foundation, yet two global megatrends are now hitting Australia - trends which will crack that foundation and may break it altogether.

The first megatrend is the rise of China, which is the most important thing to happen to Australia's security since federation. The reason it matters so much is that China is likely to become, economically and militarily, the most powerful country in the world. China won't want to play second fiddle to the United States, particularly in its own region, so the US will either have to compete with China to maintain its top-dog status in our region, or it will need to back off.

Since coronavirus hit, we've heard a lot about America's escalating rivalry with China, but the jury is still out on whether Washington is committed to long-term competition with the most powerful rival it has ever faced. In 2011, President Barack Obama came to Australia to launch America's "pivot" to Asia, but since then there have been few signs that the US is willing to commit substantial new military resources to the region to counter China's dramatic military modernisation.

Behind the scenes in Canberra, the idea that America will be a less reliable ally in future is starting to gain traction, though in their public commentary our political leaders remain steadfast alliance supporters. This is where the second global megatrend comes in, because all over the democratic West, the same force is destabilising politics: the decline of big political parties. Increasingly, voters have stopped joining these parties and stopped voting for them.

The trend is decades old, but is now big enough that it is reshaping democratic politics: in the US, the Republican Party was so weak in 2016 it couldn't fight off Donald Trump, even though the party was united against him. In the UK, the Tories were so fragile that a small faction of Eurosceptics got its way on a Brexit referendum. Around Europe, major-party decline has unlocked a small but highly motivated base of voters who now support right-wing populists.

Australians, too, are abandoning the major parties in record numbers. Thanks to our voting system, Labor and the Liberals still have a strong grip on power. But the parties are products of an industrial-age economy which is unrecognisable to modern Australians. That's why so few us join them and we increasingly don't vote for them. As a result, hung parliaments and minority governments will become the norm as high-profile independents and single-issue minor parties make up a growing crossbench in the House of Representatives. The Senate will get more unruly for governments, too.

The Labor and Liberal parties are the joint custodians of the alliance with the United States, and as their duopoly slips, the grip that the alliance has had on Australian politics will loosen with it.

When you couple the turn away from major parties with the rise of China, the future of the alliance looks highly uncertain. Public opinion won't hold back this tide, because as solid as Australians' support is for the alliance, it is unlikely to be a deciding issue when they vote. The megatrends are coming for the ANZUS alliance, and the forces supporting the status quo will be too weak to hold them back.

• Sam Roggeveen is director of international security at the Lowy Institute.