Commemorations in South Korea yesterday, and elsewhere around the world, marked the 70th anniversary of the signing of the Korean War armistice at Panmunjom on 27 July 1953. Today, amid the war in Ukraine and tensions in East Asia that could flare into hostilities, the lessons of the Korean conflict are worth close re-examination.

After three years of bloody and exhausting fighting, the armistice brought a fragile peace. With nuclear weapons having emerged as part of the deterrent suite of capabilities, the war was contained, in part resembling the front lines of World War I.

This line of demarcation established after a long and relatively static phase from mid-1951 onwards between opposing forces would become known as the DMZ—the demilitarised zone. The front line between US-aligned forces under the United Nations Command and the forces of the North Korean Army and ‘volunteers’ from the People’s Republic of China would become the de facto border between North Korea and South Korea.

The war had been fought to a stalemate roughly along the 38th parallel, its original starting point. But the 21-member UN coalition had suffered almost 800,000 military casualties—dead, wounded and missing. The vast majority—more than 600,000—came from South Korea. Meanwhile, almost a million South Korean civilians died and up to 1.5 million North Koreans and Chinese died. The United States suffered 36,574 dead and, of the more than 17,000 Australians who served there, 1,500 were casualties, including 340 killed. What this shows is that far from being a police action, it was a devastating war and one of the most important conflicts, politically and military, of the 20th century.

For Australia, the conflict set a pattern for much of the rest of the Cold War and beyond. In contrast to World War II, when Australia managed to muster (in land-power terms alone) 14 divisions as part of its land forces and deployed four or five of them at any one time, in the Korean War a much more carefully calibrated force contribution was made. In June 1950, Australia committed land, sea and air forces just as they were from the residual elements that had occupied Japan from 1946 to 1950. In time, two infantry battalions deployed (one on rotation) as part of a British Commonwealth infantry brigade, along with a squadron of fighter aircraft and a selection of Australian warships, including an aircraft carrier, HMAS Sydney.

The armistice still stands 70 years on, albeit with occasional disruptions. A few points are worth noting.

First, the United States was indispensable to the defence of Korea. An international force could not have been mustered to defend the south without US resolve to make it happen. But the North Korean leader, Kim Il-sung, likely would not have been confident of invasion success had it not been for US Secretary of State Dean Acheson’s January 1950 address to the National Press Club in Washington. There he declared, in effect, that Korea was beyond the limits of US security guarantees. Kim saw that as a sign of weakness that he could and did exploit.

Second, President Harry Truman acted, against a backdrop of public horror at the naked aggression. Visceral public sentiment hadn’t featured in the equation behind Acheson’s manifesto. Truman sent General Douglas MacArthur to rescue the situation, and his forces arrived just before the entire Korean peninsula was completely overrun. After consolidating the Pusan perimeter, his amphibious lodgement at Inchon, near Seoul, led to the unravelling of the North Korean army and the fateful decision to not only cross into North Korea but advance right up to the Yalu River bordering China.

With supreme confidence, and a belief that he was entitled to use nuclear weapons, MacArthur was prepared to stare down the Chinese. But Truman though better of that and replaced MacArthur rather than allow him to cross the nuclear threshold. That precedent still holds. No nuclear weapon has been used in anger since the bombs dropped on Hiroshima and Nagasaki in 1945. It is difficult to imagine a scenario where either side would choose to break that now nearly 80-year-old taboo—one that even Russia’s Vladimir Putin has been wary of breaking in his war in Ukraine.

Third, the armistice is just that. It is not a formal peace treaty. And with North Korean ballistic missile firings in recent times becoming more tried, reliable, longer in range and more sophisticated, coupled with Pyongyang’s continued bellicose rhetoric, the prospects of war remain alive. Most don’t realise that Australia retains significant and consequential security obligations there as part of the United Nations Command. Australia could be called to commit air and maritime forces at short notice, and Australian land forces could be in demand if the situation deteriorated significantly.

Fourth, today, while the Korean peninsula remains fraught, there are other flash points in East Asia that are equally, if not more, worrying. These include the heightened tensions over what Japan calls the Senkaku Islands and China calls the Diaoyu Islands in the East China Sea just northeast of Taiwan. There, Chinese maritime militia, armed fishing fleets and coastguard vessels have persistently harassed, intimidated and gradually worn down Japanese capabilities, if not Japan’s resolve to resist the Chinese encroachment.

Beijing’s approach of salami slicing—of engaging in persistent harassment to erode resolve and yet avoiding crossing a kinetic threshold into open warfare—appears akin to the ancient Chinese game of Go, in which players add pieces to the board and seek to flip rather than remove or destroy the pieces of their opponents. Clearly, the People’s Liberation Army is preparing for the possibility of war. But I would contend that its martial capability is informed by the vulnerabilities of China’s geostrategic challenges, its ‘Malacca dilemma’, and its reliance on trade and investment.

Then there are the contested claims in the South China Sea. Despite the 2016 arbitral tribunal ruling discounting the legitimacy of China’s claims over the territory within its so-called nine-dash line, it continues to harass and intimidate the contiguous states (Vietnam, Indonesia, Malaysia, Brunei and the Philippines) in their territorial waters and exclusive economic zones as recognised under the UN Convention on the Law of the Sea.

Finally, there’s the prospect of war over Taiwan. Here the echoes of what happened in Korea appear the most significant. Uncertainty over US resolve and support appears to have encouraged North Korea to invade the south in 1950. Popular responses drove Truman to change his policy and rapidly deploy MacArthur and his forces to defend the south. Allies and partners were promptly called upon to help in ways that appeared unimaginable only weeks earlier.

No one knows what the future holds, and history does not repeat. But its rhyming points to the utility of closely considering again the experience in Korea 70 years ago.

The three countries that started the Korean War in June 1950—Russia (USSR), China and North Korea—are still manoeuvring to secure a better outcome. When World War II ended in August 1945, American and Soviet troops had met more or less amicably at about the 38th parallel on the Korean peninsula. In 1949, both those powers withdrew their forces, leaving behind feeble local administrations in the north and the south that each aspired to lead the first government of the whole of Korea following the decades of Japanese colonial rule.

Kim Il-sung, a northerner who had fought in the resistance against Japanese rule and was accepted by the occupying Soviet forces as the leader of the north, lobbied the Soviet leader to support using force to take over the south and bring the whole of the peninsula into the socialist camp. Stalin eventually agreed that that was an attractive and feasible objective. On the condition that Kim Il-sung also secure China’s support for the venture, Stalin undertook to provide equipment, training and planning but ruled out any direct involvement by Soviet forces.

China’s Mao Tse-tung approved the plan and North Korean forces launched the attack on 25 June 1950. The north overran the southern forces, who retreated to a small enclave around the southern port of Pusan before the American-led UN forces reversed those gains and routed the north’s forces only to encounter, in October 1950,  a large force of Chinese ‘volunteers’.

This US–China phase of the conflict lasted for two more years before a truce was negotiated that recognised the original informal dividing line—the 38th parallel—as the de facto border between the Republic of Korea in the south, allied to the US, and the Democratic People’s Republic of Korea in the north, a socialist state closely tied to the USSR and China.

That truce is still in place, which means that all the belligerents are still, in formal terms, at war with one another. And the peninsula did indeed evolve quickly into an arena of essentially permanent tension, provocation and imminent conflict. The USSR and China took care to ensure that Pyongyang lacked the capacity to contemplate renewed unilateral military adventurism. That remained the case even as the DPRK veered off towards becoming the most highly militarised and uniquely repressive authoritarian regime in the world.

The narrative that underpinned the DPRK’s political trajectory has been founded on the contention that the country had narrowly escaped naked American aggression in June 1950 and that the enemy, a superpower bristling with nuclear weapons, had since embedded itself in the south while it searched for another opportunity to invade.

Russia and China have never had the courage to contest this narrative or, indeed, to seriously encourage the DPRK to take a different path. The US has for some 70 years borne the lion’s share of the burden of deterrence and alliance management emanating from the machinations of the DPRK. Even when Pyongyang began, in the late 1980s, to explore the possibility of a nuclear option, Russia and China kept their distance. China, in particular, openly informed Washington at subsequent points of nuclear crisis—notably 1993–94 and 2002—that responsibility for the issue lay with the US and the DPRK.

The DPRK conducted its first nuclear test in 2006, and others followed in 2009, 2015 (two) and 2016. It then began to work more seriously on ballistic-missile-delivery vehicles and, over the period 2012–17, demonstrated developmental progress across a family of ballistic missiles that has astonished most experts. It is astonishing because the DPRK is small, very poor and the subject of rigorous sanctions to preclude the acquisition of critical nuclear and missile technologies. Some have drawn pointed attention to the fact that nearly all of North Korea’s trade comes through China.

For those reasons, it is more than a little rich for Russia and China to advocate, as they still do, that the solution must lie in the US agreeing to meet and negotiate with the DPRK unconditionally—that is, without even an understanding that the purpose of the negotiations is to reverse the DPRK’s nuclear and missile programs.

Moreover, China and Russia insist that even with the DPRK’s astonishing progress with ballistic missiles, the deployment by the US and South Korea of a more advanced THAAD (Terminal High Altitude Air Defense) system demonstrated an unacceptable disregard for their own strategic interests in an unimpeded capacity to target the US with ballistic missiles.

Finally, it matters that Vladamir Putin and Xi Jinping want to see the DPRK and the US set the stage for negotiations, by the former freezing its missile and nuclear tests and the latter cancelling its regular military exercises with South Korea, implying equal responsibility for the enduring impasse.

Each of these postures illustrates a cavalier denial of responsibility for the DPRK and all that has transpired on the peninsula since 1950. The fact is, however, that Russia and China bear deep and significant responsibility for the current state of affairs on the peninsula.

They may hope to prolong the crisis beyond the end of American pre-eminence so that the history sketched above can be recast. But we may also be approaching a defining point. There are no attractive military options, not even for a superpower, but if the US gets to the point where it harbours doubts about the stability of the DPRK leadership and suspects that any one of several missile types could be carrying a nuclear warhead, it may feel compelled to act.

It’s only too clear that a negotiated outcome is beyond the reach of the three players most immediately involved—the US, South Korea and the DPRK. All the relevant players must bring their full influence to bear. That can’t happen if some won’t even acknowledge significant responsibility for the issue.