Washington ? A war President Bush launched expressly to rid Iraq of its weapons of mass destruction has yet to uncover any of them, and with each passing day the question grows more acute: Where are the huge caches of chemical, biological and nuclear materials Saddam Hussein is supposed to possess?

Much of the political, diplomatic and legal justification for the U.S.-led war rests on the assertion that Saddam is hiding weapons of mass destruction and has defied repeated U.N. demands to surrender them.

If that proves not to be true, the Bush administration’s diplomatic credibility would be shaken, the Muslim world would be reinforced in its belief that Washington is waging war against Islam and U.S. leaders might even be vulnerable to legal challenges in international courts.

“We know we need to find this stuff,” said one State Department official, “and we know that we will.”

Pentagon officials remain confident that they will eventually find evidence of chemical, biological or nuclear weapons. They insist that they are still deeply engaged in fighting the war and have scarcely had time to search for the banned materials, some of which Saddam may have hidden in areas of Baghdad or Tikrit not yet under their control.

“Let’s remember that this regime has been involved in a campaign of denial and deception for decades and has been very effective at it,” Army Brig. Gen. Vincent Brooks said in Doha, Qatar, on Friday.

“And so we don’t expect that we’re just going to walk up on any WMD (weapons of mass destruction). We’ll have to do things that give us control of areas that let us then do deliberate work.”

But American and British forces are operating in vast sections of northern, southern and western Iraq where intelligence sources and Iraqi defectors had reported that parts of the deadly arsenal were located, yet nothing definitive has been found.