There are two ways of looking at the case of Sergeant Bowe Bergdahl, the US soldier who was released from Taliban captivity last week in return for the liberation of five Guantanamo detainees, all reputed to be high-value al-Qaeda terrorist commanders.

Neither is particularly edifying. The first is that Bergdahl is a serving soldier and therefore the US army owed him the right not to be left behind and forgotten as a prisoner of war. Saving Private Ryan has a lot to answer for and its message was shared by Defence Secretary Chuck Hagel as well as by many high-ranking army officers.

The second point is more controversial and as it was expressed by some of Bergdahl's comrades in arms it has not only gathered momentum but it has come to be believed. In their way of thinking, Bergdahl was not a lost soldier but quite possibly a traitor who abandoned his post and left them in the lurch. To them, Bergdahl does not deserve acclaim but warrants criminal investigation. It does not help matters that six fellow soldiers lost their lives in the operation to find him.

So is Bergdahl a hero or a villain, a cold-eyed pragmatist or a holy fool? With so little known about the case and with so much innuendo swirling around it is too early to say for sure but there are some clues. By any standards Bergdahl was a bit of an oddball, not your average soldier but a young man who entertained strong feelings about his calling and the role he was playing in Afghanistan. Forget the fact that he learned Pashto, the language spoken by many Afghans: this was a good thing and had it been replicated in other soldiers the US might not have ended up facing defeat and humiliation in the country. Put to one side, too, the fact that he was disenchanted with his country's policies: many soldiers experience those kind of doubts but very few act on them.

What seems to be the case is that Bergdahl should perhaps not have been wearing the uniform in the first place. There can be no question about his physical capacities - five years in Taliban captivity would have been harsh and gruelling - but it has to be asked what was going on inside his head. Initial soundings are not promising. The son of free-thinking Calvinists in rural Idaho, Bergdahl received a home education which was strong on survival training - for example, he was a good shot by the age of five. His first thought was to join the French Foreign Legion and then he wanted to travel in Africa to teach self-defence techniques to people being brutalised by local warlords. Neither wish materialised and so he ended up in the US army.

Sent out to Afghanistan he soon began to question US motives in the country and, according to his fellow soldiers, he had announced his intention to renounce his citizenship and join the Taliban. If this was true it would have made him a traitor and a long stretch in a military prison would have awaited him. Again, if true, it beggars belief that President Barack Obama acted to help the young sergeant and in such a public way, giving the exchange huge publicity and inviting Bergdahl's parents to the White House.

As a result, what should have been a joyous occasion has turned into a policy own goal and questions are now being rightly asked about the benefits accruing from the exchange. In truth there will not be many. During his debrief, Bergdahl will be able to supply much information about his captors but this will be low-level stuff probably already known to US military intelligence and the CIA . Even as a regular soldier his days in the army will be numbered. There are so many questions over what actually happened and so many rumours to be answered that it is impossible to see him continuing in any meaningful capacity.

If anything, his experience offers a telling example of what happens to so many soldiers who are exposed to the stress of almost continuous combat in a theatre of war like Afghanistan. Is it any wonder that significant numbers return with broken minds or find themselves unable to reconcile their experiences in the warzone with the ordinary demands of day-to-day civilian life?

As for the Taliban, they will emerge with smiles from the whole business. Not only did they manage to wrest a propaganda advantage from the prisoner exchange - seeming to get the better of the US special forces during the operation - but they now have back in their order of battle five top commanders. The war might be coming to an end but it will be fought to the last and this was certainly a priceless advantage for the Afghan opposition.