WASHINGTON — U.S. Defense officials said Thursday that Iraqi insurgents have sharply curtailed the use of their most powerful roadside bombs, weapons American officials repeatedly have charged are being smuggled into the war zone from Iran.
But Defense Secretary Robert M. Gates said it was too soon to tell whether the decline in the use of the munitions resulted from an Iranian pledge to stem the flow of weaponry between the two countries. Tehran has denied that it is providing munitions to Iraqi insurgents.
The bombs, known as explosively formed penetrators, or EFPs, are a favored weapon of Shiite Muslim militias and can pierce the toughest armor the U.S. Army has fielded in Iraq.
Army Lt. Gen. Raymond T. Odierno, the day-to-day military commander in Iraq, said 53 of the armor-piercing bombs were found on roads in October -- 30 that detonated and 23 that were discovered before they exploded. That is down from 99 in July and 78 in August. In September, 52 exploded or were detected.
The decline in such attacks, Odierno said, coincided with a drop in the number of U.S. military casualties, civilian killings and overall deaths.
"I believe we have achieved some momentum," he said. "Although it is not yet irreversible momentum, this positive momentum has set the conditions for political accommodation, economic development and basic services to progress."
Gates, in a news conference later, refused to say that the developments indicated the U.S. was winning in Iraq.
The Los Angeles Times reported in September that Iraqi Prime Minister Nouri Maliki had secured a pledge from Iranian President Mahmoud Ahmadinejad to help cut off weapons, funding and other support to militants in Iraq.
"It is my understanding that they have provided such assurances," Gates said at the Pentagon, confirming the deal. "I don't know whether to believe them. I'll wait and see."
State Department officials have accused the Iranian government of allowing weapons to be shipped into Iraq. Gates said again Thursday that he had no direct evidence that top Iranian officials have knowledge of smuggling, although he suspects they do.
"My guess is the highest levels are aware," he said.
The military said armor-piercing explosives have been used by the two main Muslim sects, but are most closely associated with Iraqi militias that have ties to Iran, such as elements of radical Shiite cleric Muqtada Sadr's Mahdi Army.
