WASHINGTON — There has been a sharp decline in the number of the most deadly roadside bombs found in Iraq in the last three months, but it's unclear whether that's because Iranians have curtailed the flow of the weapons, the No. 2 U.S. commander in Baghdad said Thursday.

Last month there were 30 attacks involving what the military calls "explosively formed projectiles" (EFPs) and 23 more were found unexploded for a total of 53, said Army Lt. Gen. Ray Odierno.

That compares with 99 in July, 78 in August and 52 in September, he told Pentagon reporters via videoconference from Iraq.

EFPs fire a slug of molten metal capable of penetrating armored vehicles and so are more deadly than other roadside bombs. Officials charge that they have been supplied by neighboring Iran along with training, funding and other support for Iraq's Shiite militants.

Odierno was asked if declining violence in general among Shiites could be partly due to a reported pledge made to Iraqi Prime Minister Nouri al-Maliki by Iranian President Mahmoud Ahmadinejad to help cut off funding to extremists.

"In terms of Iran, it's hard to tell whether that has slowed down or not," Odierno said.

He said troops found a huge cache of EFPs a week ago, but believe it may have been brought into Iraq around January, before the agreement.

"So it's unclear to me whether they have slowed down bringing in weapons and supporting the insurgency or not," Odierno said. "I'll still wait and see."