Khalid Sheikh Mohammed’s confession to masterminding the 9/11 attacks and a string of other terror plots hasn’t taught us much about him that we didn’t already suspect. But it does offer a chilling reminder of how brutal and determined an enemy we face in the War on Terror.

The confession was released yesterday, as part of a government transcript of a hearing to determine whether Mohammed, once the third-highest leader of al Qaeda and now a detainee at Guantanamo Bay, can be designated an enemy combatant and tried by military commission. “I was responsible for the 9/11 operation from A to Z,” he said. He also confessed to the beheading of Wall Street Journal reporter Daniel Pearl and the 2002 bombing of a Bali nightclub that killed 202 people.

All this is, as we said, no surprise. What’s startling about the confession is the glimpse it gives us of how much worse things could have been. Mohammed said he was plotting to attack the Sears Tower, the Empire State Building, the New York Stock Exchange, the Panama Canal, Big Ben, and Heathrow Airport. He wanted to assassinate Jimmy Carter, Bill Clinton, and Pope John Paul II. He planned to blow up nuclear power plans in the U.S. and suspension bridges in New York. None of these plans succeeded, but there’s no reason they couldn’t have—and every reason to think that al Qaeda is hard at work plotting equal or worse destruction.

The usual suspects on the Left are obsessing over Mohammed’s claim, according to the transcript, that he was once tortured by the CIA (though the same transcript has him saying, as he confesses to 9/11 and the other attacks, that he is not speaking under duress). It has been widely reported that he was subjected to the extremely harsh technique of water-boarding shortly after his capture. This, along with the barring of reporters from the recent proceeding, has led some to suggest that the confession is somehow bogus. Their argument is unpersuasive for two reasons.

To understand the first, recall the trial of 9/11 conspirator Zacarias Moussaoui. Moussaoui wanted to call Mohammed as a witness in his defense. Why? Because Mohammed had told government interrogators that Moussaoui had had nothing to do with 9/11. In the end, Mohammed didn’t testify at the trial. But if the government were in the business of torturing people to make them say what it wants, surely it wouldn’t have kept records of Mohammed’s claims that Moussaoui was innocent, let alone permitted Moussaoui’s defense to learn about them.

More important, the government would have had no motive to force Mohammed’s recent confession, for the simple reason that it was not necessary. There was already more than enough evidence to convict him of 9/11 and other attacks. Don’t forget that Mohammed was indicted in 1996 in connection with “Operation Bojinka,” a plot to blow up a dozen U.S. commercial airliners. (In Arabic slang, “bojinka” means “explosion.”) The plot was never executed, but the terrorists tested their explosives and killed a man in the process. If tried for his role in the Bojinka plot, Mohammed could have faced the death penalty (though he probably would have been sentenced to life imprisonment, as were some of his co-conspirators). An abundance of evidence linking him to 9/11 has also emerged. We didn’t need yesterday’s transcript to tell us what he has done or to hold him accountable for it.

There’s little doubt as to the outcome of the hearing: Mohammed will be designated an enemy combatant and eventually tried by military tribunal. He deserves a swift and relentless justice. His value as an intelligence asset is probably exhausted. Having been in custody since 2003, he has likely said everything he is going to. Nor can he offer useful information about al Qaeda plots hatched since his detention. His crimes are acts of war and worse, for his specialty was the slaughter of civilians. Thousands are dead because of him. Thousands will die yet if we slacken in our resolve to defeat his comrades still plotting against us.