Why do you think your novel, Matterhorn, which is set during the Vietnam war, had such an extraordinary reception in the United States?
I think it was because the parallels between Afghanistan and Vietnam are uncanny. Just go down the list: they can run across the border and we can't; the government, which is on our side, is corrupt; we stick out like sore thumbs, and they don't; we don't know how to speak the language. What are we doing? We went over there to get Osama Bin Laden, who wasn't there. Well, now what?
And I think the other reason it's resonating so much is that the baby boomers are now mature and they're starting to wonder: "What the hell happened?" I think that, whichever side they were on of that horrible chasm which split our country, people are now trying to reconcile.
Were those arguments about the war in your mind when you fought in Vietnam?
By the time I was there it was 1969. So, yes, they were. I was from a little town in Oregon and I still had high hopes that the president wouldn't lie to us. But you get over there and you don't know what you're doing except killing people, and that doesn't sit right. The novel isn't really a political book - it's about kids growing up - but the politics were part of the zeitgeist.
So you took the fraught politics of the US in the late Sixties into the jungle with you?
Absolutely. Our brothers and sisters were back home on the streets rioting. My own brother, for example, figured out how to dodge the draft. He managed to do it because he was an extraordinarily good football player, an all-state quarterback.
How tense were the racial politics out there?
Vietnam was the first time that Americans of different races had to depend on each other. In the Second World War, they were segregated; it was in Vietnam that American integration happened in the military - and it wasn't easy. There were over 200 "fraggings" [murders of superiors] and almost all of them were racially motivated.
There was an enormous amount of tension. Think about what America was experiencing then. Watts was going up in smoke; Detroit was burning down; in Newark they had snipers shooting; you didn't know if the Black Panthers were gonna take over the country. And there you are in Vietnam. If you think you had racial tension in America, take 19-year-olds [to the jungle], give them all automatic weapons and say, "Here, live together," when they'd never lived together before. Holy shit!
What are the differences between the experiences you and your characters had in Vietnam and those of US troops today in Iraq and Afghanistan?
There's a huge difference. Where the marines were - I was where the novel is set, in the mountains north of Khe Sanh - we were just facing the North Vietnamese army. If there was something moving in the bush and you knew it wasn't your guy, you'd just shoot it. Today, you're asking teenage kids to make decisions that are beyond belief. Somebody shows up and they don't know if they're the enemy or not. Adults shouldn't put kids in situations where they don't know who the enemy is.
Were you never in that situation yourself?
I was very fortunate, in that I never had that psychological problem of wondering if I'd killed someone who was not my enemy. It's bad enough when I think back about people I killed. I think it over and realise that they were just children. It's circumstance. I could have been born Vietnamese, and I could be dead by now.
Do you think often about the people you killed?
I think about the war experience daily and I think about dying all the time - two or three times a day. Before the war, I didn't have that. I'll be having a wonderful time with my kids, and then all of a sudden I'll be aware that this is temporary and I'm going to die. If I think about the war, I don't think about the people I killed. But every now and then it comes up, and I start thinking about it and saying to myself, “I did a lot of damage." I don't believe it's guilt - I believe it's sadness. Because they were trying to kill me. But for what? Vietnam's going capitalist and now they're fighting with China.
Karl Marlantes's "Matterhorn" is published by Corvus (£16.99)