During a visit to the main British base in Afghanistan, Camp Bastion in Helmand province, Mr Hammond suggested that there was a feeling of war-weariness among those countries which have been engaged in almost continuous conflict since the 9/11 attacks on the US in 2001.
"I suspect that the British people - and not just the British people - will be wary of enduring engagements on this kind of scale for perhaps quite a long while in the future," he said in an interview with The Daily Telegraph.
Britain may be wary of taking on future lengthy military commitments, Defence Secretary Philip Hammond said
"You might call it the Vietnam phenomenon - when an engagement turns out to be longer and more costly than originally envisaged, there is often a public reaction to that."
However he said that the true lesson from Afghanistan may be that a prolonged military commitment could have been avoided if the West had been prepared to intervene earlier before al Qaida launched its attack on the Twin Towers.
"We ourselves have learned the lesson that earlier, smaller scale intervention may often avoid the need for more massive intervention later, and if we are in a mood for beating ourselves up, perhaps we should have foreseen the consequences of what was happening in Afghanistan before 9/11," he said.
"Perhaps we should have been more forward leaning in the West collectively in intervening to try and head off what was happening here before it happened."