Whoops, Saddam had WMDs after all

George W Bush wasn't lying about Iraq after all, and those of us who said that he was owe him an apology. Saddam Hussein did have weapons of mass destruction. We just didn't read the small print.

When President Bush said in a speech: "Facing clear evidence of peril, we cannot wait for the final proof - the smoking gun - that could come in the form of a mushroom cloud," we thought that he was talking about nuclear weapons. And many of us didn't believe him.

When Vice-President Dick Cheney assured us: "There is no doubt that Saddam Hussein now has weapons of mass destruction. There is no doubt he is amassing them to use against our friends ... and against us," we just assumed he was lying as usual.

And when Colin Powell, the secretary of state, told the UN Security Council that "Saddam Hussein and his regime are concealing their efforts to produce more weapons of mass destruction ... We know that Iraqi government officials ... have hidden prohibited items in their homes," we thought he meant nukes and poison gas and nasty biological agents. Poor old Colin, we thought. An innocent soldier, too gullible for his own good.

But we were all wrong. The real threat was pressure cookers, and there were thousands of them in the homes of Iraqi officials.

We shouldn't be too hard on the Bush gang for not making full disclosure of what they actually meant by "weapons of mass destruction" at the time. Imagine how silly Colin Powell would have looked at the United Nations if he had shown the disbelieving audience not a vial of suspicious-looking liquid (nerve gas? bubonic plague?), but merely a pressure cooker. But there can be no doubt now: there WERE "weapons of mass destruction" in Iraq.

These penitential thoughts are inspired by the charge brought against Dzhokhar Tsarnaev, the surviving brother of the two young Chechen-Americans who detonated two pressure cookers stuffed with explosives and ball-bearings at the Boston Marathon last week, killing three and wounding several hundred. It was a wicked deed that brought great sorrow to many families - but are pressure cookers really "weapons of mass destruction"?

The US Department of Justice certainly thinks so. On 22 April it charged the 19-year-old Tsarnaev with "using and conspiring to use a weapon of mass destruction against persons and property". Not a nuclear weapon, or poison gas, or some filthy plague, but a home-made bomb that killed three people.

The US federal government's definition of a "weapon of mass destruction", it turns out, is quite different from the one we ordinary mortals use. It covers almost any explosive device, specifically including bombs, grenades, mines, and small rockets and missiles.

The requirement seems to be that the weapon in question has to explode, so assault rifles with large magazines, for example, are exempt, even though they have been used to kill much larger numbers of innocent American civilians on several occasions. (Mustn't upset the National Rifle Association.)

Of course, AMERICAN bombs, grenades, mines and small rockets and missiles are not "weapons of mass destruction". That would be unthinkable. Otherwise we would have to accept that President Barack Obama signs off on the use of drone-delivered weapons of mass destruction on the guilty and the innocent alike in Afghanistan, Pakistan and Yemen almost every morning.

What's really going on here is just another manifestation of what Americans themselves call "American exceptionalism". In this context, it means that killing Americans, especially for political reasons, is a special crime that calls for special terms and special punishment. It's the same logic that has been used to justify imprisoning people indefinitely without trial and even torturing them in the endless "war on terror".

Don't get too excited about it. One of the things that makes Americans completely unexceptional is that they are playing the same games with words and meanings that every great power has used to justify its actions since the dawn of time. Lewis Carroll nailed it a century and a half ago in Through the Looking-Glass, the sequel to Alice's Adventures in Wonderland.

"When I use a word," Humpty Dumpty said, in a rather scornful tone, "it means just what I choose it to mean - neither more nor less."

"The question is," said Alice, "whether you can make words mean so many different things."

"The question is," said Humpty Dumpty, "which is to be master - that's all."

•Gwynne Dyer is an independent journalist whose articles are published in 45 countries.