Democratic presidential candidate John F. Kerry charged today that President Bush committed a great blunder and demonstrated "incredible incompetence" by failing to secure tons of explosives in Iraq that are now missing and potentially in the hands of terrorists.

Using some of his harshest language of the campaign to condemn his opponent, the Massachusetts senator said the episode shows that Bush has failed "the test of being the commander in chief."

In a speech to supporters at a high school in Dover, Kerry referred to a story on CBS's "60 Minutes" and in this morning's New York Times detailing the Bush administration's failure to secure nearly 380 tons of highly dangerous explosives after the fall of Baghdad.

The International Atomic Energy Agency officially reported the materials' disappearance to the U.N. Security Council this afternoon. The highly explosive materials were stored at a former Iraqi military facility that once played a key role in the efforts of Iraqi president Saddam Hussein to build a nuclear bomb, the IAEA said.

The Iraqi Ministry of Science and Technology informed the IAEA on Oct. 10 that about 350 metric tons of explosives -- equivalent to about 380 U.S. tons -- had been looted and were missing.

"George W. Bush, who talks tough -- talks tough -- and brags about making Americans safe, has once again failed to deliver," Kerry said. "After being warned about the danger of major stockpiles of explosives in Iraq, this president failed to guard those stockpiles where nearly 380 tons of highly explosive weapons were kept. Today we learn that these explosives are missing, unaccounted for and potentially in the hands of terrorists. Terrorists could use this material to kill our troops, our people, blow up airplanes and level buildings."

Kerry added, "Now we know that our country and our troops are less safe because this president failed to do the basics. This is one of the great blunders of Iraq, one of the great blunders of this administration. The incredible incompetence of this president and his administration has put our troops at risk and put our country at greater risk than we ought to be."

In a 45-minute speech in Greeley, Colo., today, Bush ignored the news about the missing explosives, Washington Post staff writer Mike Allen reported. Instead, Bush stuck to his stock assertion: "America and the world are safer with Saddam Hussein sitting in a prison cell." The line drew applause from crowd packed into a rodeo arena, where Bush was flanked by a huge sign saying "Leadership Matters" and vertical banners reading, "Character," "Leadership" and "Strength."

Explaining Bush's omission of any reference to the missing munitions, a senior administration official said Bush rarely mentions the news of the day in his speeches.

"He's never been a play-by-play guy," said the official, who refused to be identified in order to speak more candidly. "We would like John Kerry to talk about his record and his strategy for Iraq, but he's not doing that, either."

White House press secretary Scott McClellan said the administration had been informed about the missing explosives on Oct. 15 and that national security adviser Condoleezza Rice "was informed days after that."

"She informed the president," McClellan said. He said munitions "sites now are the responsibility of the Iraq government to secure."

White House communications director Dan Bartlett said that munitions in Iraq have been a priority for the administration, asserting that more than 10,000 caches totaling more than 243,00 tons have been destroyed. Most of those were low-grade explosives, such as mines.

Bartlett said the administration did not put out the information earlier in part because the White House wanted "to get all the facts and find out exactly what happened in this case," as well as whether there are other missing stockpiles. "So doing it piecemeal, I don't think would have been the responsible thing," Bartlett said.

In his speech in Dover, Kerry said the Bush administration has repeatedly "miscalculated" in Iraq and that Defense Secretary Donald H. Rumsfeld had "cavalierly dismissed the danger of looting" after the fall of Baghdad in April 2003. "And now we know the impact," Kerry said.

"The unbelievable blindness, stubbornness, arrogance of this administration to do the basics has now allowed this president to once again fail the test of being the commander in chief," Kerry said.

"If the president can't recognize his failures in Iraq, which he doesn't admit and won't acknowledge, you can't fix them, and then he's doomed to repeat the same mistakes elsewhere," the senator said. "We can't afford to risk four more years of George Bush's miscalculations."

The missing explosives, which had been stored at the sprawling al Qaqaa military installation about 30 miles south of Baghdad, included HMX and RDX, which can be used to demolish buildings, down jetliners, produce warheads for missiles and detonate nuclear weapons, the Associated Press reported. HMX and RDX are key ingredients in plastic explosives such as C-4 and Semtex -- substances so powerful that Libyan terrorists needed just one pound to blow up Pan Am Flight 103 over Lockerbie, Scotland, in 1988, killing 170 people, the agency said.

In addition, HMX can be used to create an explosion powerful enough to trigger the fissile material in a nuclear weapon, setting off a chain reaction.

Al Qaqaa came under U.S. military control after last year's invasion but has been repeatedly looted since then.

Because of the dual-use nature of some of the explosives there, the IAEA had monitored them before the war. But the agency's inspectors pulled out of Iraq just before the invasion and have not yet been able to return.

Before the invasion, Iraq declared that the HMX previously under IAEA seal had been "transferred for use in the production of industrial explosives, primarily to cement plants as a booster for explosives used in quarrying," IAEA Director General Mohamed ElBaradei told the United Nations in February 2003.

The disclosure that the explosives were missing immediately became fodder for the U.S. presidential campaign, which has focused to a large extent on the war in Iraq and national security issues.

During an appearance in Toledo, Ohio, Kerry's running mate, Sen. John Edwards of North Carolina, echoed Kerry's criticism by proclaiming that the missing explosives were more evidence of Bush's "grave incompetence" in Iraq, Washington Post staff writer John Wagner reported.

"About one pound of this stuff was what it took to bring to down Pam Am Flight 103," Edwards told a union crowd of close to 3,000 people.

Edwards also used the occasion to blast Bush's national security adviser for a scheduled appearance today in Florida.

"Today Condoleezza Rice is not in the situation room," Edwards said. "She's not figuring out what went wrong or how it went wrong or how we're going to find this material. No, she's in Florida, campaigning for George Bush."

A senior adviser to Kerry, former White House press secretary Joe Lockhart, said in a statement that "the Bush administration must answer for what may be the most grave and catastrophic mistake in a tragic series of blunders in Iraq." He demanded to know why the explosives were not secured and whether there was a cover-up by national security officials in the administration.

"The Bush administration knew where this stockpile was, but took no action to secure the site," Lockhart said. "They were urgently and specifically informed that terrorists could be helping themselves to the most dangerous explosives bonanza in history, but nothing was done to prevent it from happening.

"This material was monitored and controlled by U.N. inspectors before the invasion of Iraq. Thanks to the stunning incompetence of the Bush administration, we now have no idea where it is. We need to know what the administration knew about this and when. We need to know why they failed to safeguard these explosives and keep them out of the hands of our enemies."

In a reference to Rice, Lockhart said, "The national security adviser should be at her desk in Washington tomorrow to work this problem and answer these questions, instead of giving speeches in battleground states."