Question: What is Australia's longest running war? If your response was Afghanistan, you are sadly wrong. Despite nearly two decades involved there, that's not it.

The answer is our near 70-year conflict with North Korea.

Despite most of the fighting ending with the signing of an armistice back in July 1953, officially Australia is still at war with the country.

Mike Kelly is an historian with the Australian War Memorial.

"All arms of the Australian services served in Korea," he tells me in the Korean war exhibition at the memorial.

"Of about 17,000 men and women in total serving in the Army, Navy and Air Force, 340 were killed, including 43 [who went missing]."

Mike Kelly says Australia is "not at peace" with North Korea. ( ABC News: Andrew Kennedy )

And while many Australians have no idea about that vicious conflict, fewer still are aware of our continuing obligations.

"If anything untoward did happen and North Korea crossed the border, we are still obligated to assist the republic of Korea," Mr Kelly explains.

I ask: "So, officially we're still at war with North Korea?"

"Very much, it's not at peace," he says bluntly.

Battlefield nightmare

From the first bone-crunching handshake, it's clear retired Army Brigadier Colin Kahn has not faded with age.

Nor have his experiences as a professional soldier in Vietnam and Korea left him with the crippling pain such tough times would entitle him to.

Despite his near-death experience, Colin Kahn doesn't see the Korean war as a terrible time. ( ABC News: Andrew Kennedy )

Fresh out of officer training at Duntroon, he was sent to the battlefields of Korea in 1952.

The intervention of the Chinese "volunteers" had added yet another complication for the Australians and all the other allied nations.

When Brigadier Kahn and his platoon came under fire from a Chinese unit, he says he was hit in the opening burst.

"I got hit by a machine gun through the chest and a grenade on my back and I went down," he says.

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"I had left my body and I could see this battle and was wondering what the hell [was] going on down there.

"I was happy looking down at the battle but then, all of a sudden, I thought of my wife.

"I'd just been married a week before I'd left for Korea and I thought if I stay up here and feel too good about this I mightn't get back and I'll never see my wife again, so I said, 'Get me back to Earth'.

"And sure enough, I landed back there and had a bit of pain on the ground."

While Brigadier Kahn survived, of his 30 fellow classmates from Duntroon sent to the Korean War, all were either killed, wounded or taken prisoner.

Despite those tragedies and his own near-death experience, he doesn't see the Korean war as a terrible time.

He was a soldier, and it was Korea that introduced him to the sharp end of his profession.

But Brigadier Kahn's optimism fades when talk turns to the question of whether next week's summit between US President Donald Trump and North Korean leader Kim Jong-un is capable of producing a lasting peace.

He says the North Korean regime would be wary of allowing its people to be exposed to the reality of modern South Korea.

"They would find it difficult to see the great freedom and the advantages made in the south and the people would see what they're really lacking up north," he says.

"I think that's going to be a problem that's somehow got to be overcome."

Hope for the future

If Brigadier Kahn's pessimistic instincts are proven wrong and there is a lasting peace, then with the war's end would come the possibility of finding the remains of at least some of the 43 missing Australian servicemen.

"One of my closest friends from Duntroon is one of those missing people, a fellow by the name of Jeff Smith," he says.

"His body has never been recovered and for him alone I would love to see that able to take place."

As for the possibility of another shooting war involving Australia, Mr Kahn says simply: "I'd hate to think it would happen again."

Avoiding that scenario may well depend on the success or otherwise of the Hanoi summit — but Mr Trump and Mr Kim are burdened by 70 years of mutual distrust.

In the meantime, Australia, the region and the world will keep hoping that somehow a real and lasting peace can be found.

Otherwise a new generation of Australian servicemen and women may one day get the call their grandparents answered way back in 1950.