It’s galling that Khalid Sheik Mohammad has still not been convicted, sentenced and executed for his admitted role as the mastermind of the 9/11 attacks on America, despite being in U.S. custody for more than 9½ years. But it’s utterly infuriating that during a pretrial hearing Wednesday at Guantanamo Bay, Cuba, the unrepentant defendant adopted a prosecutorial tone of his own.

The al-Qaida big shot, who also has admitted to a central planner’s role in the 1993 bombing of New York’s World Trade Center, charged through a translator that U.S. presidents have used “national security” as a pretense for various outrages:

“Every dictator can put this definition on as a shoe that he chooses to step on every person in this world, every law, and every constitution. With this definition many can invade the rule and also go against it. Many can kill people under the name of national security, and torture people under the name of national security, and detain children under the name of national security.”

KSM later added: “We are all human beings.”

So were the nearly 3,000 Americans killed by al-Qaida operatives on 9/11.

At least Judge James Pohl, the Army colonel who unwisely allowed that offensive outburst to continue for almost two minutes, responded by saying:

“We need to make something clear here. This is a one-time occurrence. If the accused wish to represent themselves as attorneys that is one issue, but however heartfelt, I am again not going to entertain any personal comments by the accused.”

At least this long-overdue trial of KSM and four alleged co-conspirators is being conducted by a military commission in Guantanamo. Attorney General Eric Holder absurdly pushed for two years to hold it in a civilian court in New York City, not far from the scene of the mass-murdering crime,

Prominent New York Democrats, including Sen. Charles Schumer, were among those who talked the Obama administration out of that ridiculous idea.

Yet the world’s strongest nation — still the U.S. — looks quite weak-willed after so long postponing the trial to hold those who slaughtered thousands of our innocent civilians to full account.

Meanwhile, though Republicans rush to point fingers of blame at the Obama team for this appalling delay, remember, KSM was captured nearly six years before the current president was sworn in.

Then again, when it comes to achieving justice for what happened on 9/11/01, better late than never.

And when it comes to KSM’s rabid expressions of contempt for U.S. policy, better to tell him to shut up.

It’s a trial, not a stage.