'Drop the bomb, exterminate them all' (SPOILERS)

In my opinion Kurtz wasn't talking about his compound or even necessarily his VC enemies. During the Cold War "The Bomb" was slang for nuclear weapons. I think Kurtz wrote that in a moment of frustration. It was written on a multiple page document that he had been working on. I think he saw the futility of his efforts and perhaps even the futility of the human "experiment" and scrawled that in a burst of emotion.

As someone else said, during the Cold War "the Bomb" was often used to refer to nuclear weapons. Just look at the film Dr. Strangelove or How I Learned To Stop Worrying And Love The Bomb, it's in the title and throughout the film they just refer to nukes as "the Bomb."

Kurtz is shown to be psychologically unstable, because he's not simply going overboard with cruelty or becoming blood drunk, he's intelligent and sane enough to rationalize his actions as necessary to winning the war. However, the Montagnards and American defectors all view him as a god, and Kurtz is realizing that he can't even maintain his own ideology anymore. He still thinks of himself as fighting a war, but his followers think he's a god. He views himself as an American soldier, but the military wants him dead and there's no way he can ever return to his wife and child.

That's the only reason Kurtz dies, he wants Willard to do it. As Willard says, "Even the jungle wanted him dead. That's the only one he took orders from anyway."

What's this have to do with "Drop the bomb, exterminate them all?" It ties in to how Kurtz still has a part of him that views himself as fighting a war. He hasn't gone native, married a local woman or converted to a Montagnard religion. He still views himself as trying to win, but he's become so lost in insanity and cruelty that he's not really fighting the war anymore. And since he's become so self-destructive, the only logical answer is a nuclear weapon. In Kurtz's eyes, the U.S. military can't win with their style of warfare, and Kurtz's style is extremely effective but now he's just as bad as the VC.

Plus the last line we hear from Kurtz as Willard approaches is "They train young men to drop fire on innocent civilians but won't let them write f###, on their airplanes," with "drop fire" possibly referring to nuclear weapons or napalm. It's subtle but the fact Willard finds a note afterwards referencing "the Bomb" and the word "exterminate" specifically, further hints that Kurtz meant nukes. Kurtz was sick of everything and wanted to wipe it clean.

Can't be too careful with all those weirdos running around.

This line comes from the source novel, Heart of Darkness. In the novel, Kurtz writes about natives in Africa but adds a postscript: "Exterminate the brutes." The intention is to show the possibility of a darker more racist side to Kurtz unlike the god-like savior that many of the Vietnamese consider him to be.

I always thought he wanted him to call in the airstrike and take out the compound. Kurtz hates himself and everything he's done but at the same time he couldn't stop, he just wanted to go out like a soldier.

My interpretation is when everyone bowed down to Willard at the end they saw him as their new leader as he was the one who took out Kurtz, but then Willard lays down his weapon and everyone else follows meaning he has resisted "the heart of darkness" and won't become like Kurtz, then on the boat he turns off the radio meaning he has also resisted the urge to become like Kurtz and just bomb the entire compound. But then we hear "the horror, the horror" going in in Willards head and we can see Helicopters bombing trees so I'm not sure if Willard truly did resist "the heart of darkness"

It's Kurtz last order, his last sane thought. I get reminded of "Bridge On The River Kwai" when Nicholson says "My God what have I done"...

He was expressing the frustration that he (and others) felt over having to fight a no-win war.