Seventy-five years ago, on December 7, 1941, Japanese fighter planes attacked American warships at anchor in Pearl Harbour, Hawaii. They attacked Manila, Hong Kong and Guam hours later, but it was the attack on the American naval base that history has preserved, in the memorable phrasing of president Franklin Roosevelt, as a “date which will live in infamy”.

There’s not much sign yet that the next president, Donald Trump, has noticed this anniversary. Nor is his rhetoric quite as commanding as Roosevelt’s. Tweeting “Sad!” doesn’t quite match up to “We have nothing to fear but fear itself.”

But, like Roosevelt, he has taken to rethinking Asian geopolitics, with his phone call with Taiwan’s President Tsai Ing-wen and his follow-up comments about China being a country that snatches away US jobs while building up its strength in the South China Sea.

Trump might do well to reflect on the legacy of Pearl Harbour. It was a moment whose effects are still very much with us today. It was a pivotal historical moment for a simple reason: it was the moment that two wars – Hitler’s war in Europe and the Japanese aggression in Asia – came together into a world war (Hitler helpfully declared war on the United States a few days after the Japanese attack, giving Roosevelt an easier path to involve the US in Europe as well as Asia.)

‘Beijing should not overreact’ to Trump-Tsai phone call, says US President-elect adviser as he visits Taiwan

The war lasted four more years, but the regional order that it bequeathed in 1945 has been with us, in some form, for more than seven decades.

During the cold war, many things changed: China was isolated for nearly a quarter of a century and then reversed course to become a superpower; countries such as the Philippines and Indonesia democratised (or re-democratised).

But one thing remained constant. The region was underpinned by its relationship with American power.

WATCH: Trump talks by phone with Taiwanese president Tsai Ing-wen

The price that the US had paid in blood and treasure during the Pacific war funded a system that, ironically, made a country in North America the most powerful actor in the Asia-Pacific.

American power in Asia was not always attractive. It supported nasty regimes like South Vietnam and pre-democracy South Korea. And its obsession with communism sometimes seemed pathological. But it also supported Japan’s democratisation – probably the single most important shift in regional politics in the second half of the 20th century – as well as eventually supporting liberal change in Taiwan and South Korea.

Under Nixon, it socialised China back into the regional order, at a time when a war between China and the Soviet Union seemed quite likely. It was something of an American triumph that for much of the cold war, the Chinese and Russians distrusted each other much more than they did the Americans.

By the turn of the 21st century, Asia’s stability rested on three pillars: the growth of Asean as a balance to China; growing economic interdependence; and American military power as a stabilising force.

For those who remembered Pearl Harbour – and cold war leaders who served in the second world war in Asia included Nixon and Japanese prime minister Tanaka Kakuei, among others – the lesson of the history of prewar Asia was that economic isolationism led to imperialistic, brutal politics and, eventually, to war.

The major actors – Japan, the US, the British Empire – didn’t know how to read each other’s actions, fuelling mutual suspicion and conflict.

WATCH: US reaffirms ‘One China’ policy after Trump’s Taiwan call

All of which makes Trump’s latest gestures so hard to fathom. By setting up a call with Tsai in Taiwan, he appears to want to show that the US values Taiwan as an ally. It would be understandable if Trump wanted to show solidarity with a liberal democracy in the region, but his own logic – filtered through Twitter – seems more aimed at poking a stick in China’s face.

Which might be gratifying for him, until he needs China’s help with another rather less liberal regional actor – North Korea. Trump has argued that he and North Korean leader Kim Jong-un could sit down together and negotiate on nuclear weapons. No doubt, but he might just find it helpful to have a Chinese diplomat, rather than Kim’s favourite basketball player Dennis Rodman, in the room with him.

More worryingly, Trump’s action suggests a lack of concern for Washington’s other allies in the region. Neither Japan nor South Korea is likely to think Trump’s rhetoric helpful in balancing their relationship with their giant neighbour.

America’s policy on Taiwan and China needs to change with the times

The great criticism of China’s behaviour in the region is that it often seems unpredictable. It now seems a Trump-led US will follow the same path.

Asia is a very long way from being the cauldron that boiled over in 1941. But having not one, but two great powers in the region whose behaviour is consistently inconsistent runs the danger of sending the temperature uncomfortably high.