Another year, another spring offensive. The massive truck bomb that detonated in Tuesday’s morning rush hour followed by gunfire, killing 28 and wounding hundreds more, was sadly nothing new for the Afghan capital. More than 15 years after Western leaders declared victory over the Taliban in Afghanistan, the insurgents now control more territory than at any time since.

In Britain, the attack did not even make the lunchtime news. Western leaders want to pretend the war is over and the media has been falling in line, even though 12,000 NATO troops are still there, including 9,800 Americans and 500 Brits. The wife of one deployed British soldier told me the Post Office refused to take her care package, assuring her “all the troops left long ago.”

Instead the focus is on ISIS and Syria and dealing with the wave of refugees overwhelming Europe.

Yet, the second biggest group of people fleeing their homeland are Afghans. Last week on the Greek island of Lesbos, waiting for the Pope to come and play Good Samaritan in a detention camp, I met newly arrived Afghan families who had made the 3,000 mile journey. They included a widow and her two sons who had sold their house to raise the $20,000 cost.

The only good thing they had to say about the NATO presence was it had brought in mobile phones that enabled them to join Whatsapp to plan their migration.

They had left despite the likelihood that Europe will send them back. “If your apartment is burning you are going to jump out even if in doing so you might lose your life,” said the elder son.

Not only are the Taliban on the up in places where they never were, but ISIS has also been carving a foothold in eastern Afghanistan.

Are we in danger of losing the place where all this started – the land we swore would never again be left as ungoverned space in which terrorism could flourish? It’s common to trace the beginnings of ISIS back to the war in Iraq but its founders cut their teeth in Afghanistan—as did one of the main jihadi recruiters in the now infamous Brussels suburb of Molenbeek which spawned the Paris attacks.

If Afghanistan is lost that’s very sad for not only did we lose many lives and spend billions of dollars there but it once seemed a great success. Happy endings are few and far between in my job as a war correspondent yet back on Christmas Eve 2001, I remember sitting on the roof of Kabul’s Mustafa Hotel looking out over the hills and thinking this was one. Music, long banned by the Taliban, was blaring up from the street. The first snow was falling and children playing.

Just 60 days after the first US bombing raid following 9/11, the Taliban regime was gone, far quicker than Pentagon estimates. They had been driven out by a combination of B52 bombers and Afghan fighters, as well as buying off commanders with CIA dollars in a latter-day version of the Great Game. Lt Colonel Rob Fry, commandant of the Royal Marines at the time, told me; “We thought we’d found the philosopher’s stone of intervention.”

So what went wrong? How did we turn success in Afghanistan into defeat?

In the end 140,000 NATO troops with the most sophisticated weapons on earth failed to overcome a bunch of supposedly ragtag guerrillas led by a one-eyed mullah whose own followers described as “dumb in the mouth” and who later turned out to be dead.

If we understood why, we might understand why it is we can’t end wars any more.

In my view the problem was political more than military. As Gen Macarthur said “it is fatal to enter any war without the will to win it.” After the initial stage, we never really knew what we were trying to do—and we didn’t understand what we were going into.

People have questioned why we hadn’t learnt from history. Britain had after all fought three Afghan wars of which it lost two. And there was a more recent experience. If you go to Herat, a warlord called General Wahab has built a rotunda on a hill containing the extraordinary Jihad Museum.

It houses captured Soviet weapons, tanks, Mig fighter jets and a garish gallery of warlord portraits. Under the dome is a gruesome sound and light display of how the Russians were defeated, complete with bullet sounds and bloodcurdling screams.

“We also have an actual live Russian,” boasted Gen Wahab. It turned out the guide is a Russian who was taken prisoner and stayed on.

“When he dies will be buried here and then we will have a dead Russian”, he added.

No one can visit that museum and think invading Afghanistan is a good idea. Yet the point, says Gen Wahab, is not triumphalism. “The point is to show the new generation they should not go back to fighting.”

Afghanistan has a very young population—70 per cent of the people there are under 30. Most don’t want to go back to fighting. But they need opportunities. Without them, they join Taliban or ISIS or use those mobile phones to look abroad and decide to leave.

Lamb is the author of Farewell Kabul; From Afghanistan to a More Dangerous World, forthcoming from HarperCollins on May 3.