Hans Blix, the seemingly unflappable former Swedish diplomat who is the United Nations’ chief weapons inspector, has been a bit testy lately, and with good reason. He is angry that his agency has been shut out of the postwar search for weapons of mass destruction in Iraq. Shut out and tarred and feathered.

When Mr. Blix and others suggested shortly after the war ended that United Nations inspectors should be allowed to return to Iraq to resume their search for chemical, biological and nuclear weapons, his credibility was called into question in a series of newspaper articles and opinion pieces. Now Mr. Blix, who retires today from the United Nations job, is fighting back.

“I have my detractors in Washington. There are bastards who spread things around, of course, who planted nasty things in the media, not that I cared very much,” he recently told London’s Guardian newspaper.

Asked by CNN last week about such harsh language, Mr. Blix said he didn’t think his comments would be printed in America. Thanks to the Internet and an increasingly global media, they were. But whether Mr. Blix cares about what is said about him matters little. What matters is that he and his cadre of inspectors were shut out of the weapons hunt for what looks more and more like political reasons; to let him back into the process would be to admit that he was right to say he needed more time before the war to hunt for the weapons, much as the administration now is saying it needs time. The war against Saddam Hussein was fought on the idea that he posed an imminent threat to his neighbors and the United States because he had weapons of mass destruction. After two months of searching, U.S. forces in Iraq have found no conclusive proof that Mr. Hussein possessed any such weapons.

A diplomat by training, Mr. Blix isn’t one to say “I told you so,” but he is increasingly eager to point out that the promised stockpiles of weapons haven’t been found because, as his inspectors found out, they didn’t exist. It is possible that Mr. Hussein had or was developing a program to develop chemical or biological weapons, but this is not what the Bush administration said. It said he already had these weapons and talked ominously of a “mushroom cloud.”

As Mr. Blix leaves his New York office and returns to Sweden, the world can only hope that he will continue to speak out on this issue. The world needs to know the truth about it. Congressional hearings now under way on whether U.S. intelligence reports were accurate or hyped may address some of these concerns – if what they learn is shared with the public. The Bush administration and others must keep in mind that the credibility of the United States is at stake. If they were wrong about Iraq, their charges that Iran – the latest object of concern at the White House – has weapons of mass destruction won’t be taken seriously.

Mr. Blix may be leaving America, but his sentiments will remain in the country for a long time to come.