U.S. Defense Secretary Robert Gates says he believes the top Iranian leader is aware of the effort by the country's elite Quds Force to help Shiite insurgents in Iraq. And he confirmed that Iran's president has promised to try to stop the flow of weapons and other types of support. VOA's Al Pessin reports from the Pentagon.

At a news conference Thursday, Secretary Gates said he believes senior Iranian leaders probably are aware of the support their elite Quds Force provides to Shiite militias in Iraq. "I believe that certainly the leadership of the Quds Force is aware of this. Whether (Ayatollah) Khamenei is aware, I think you'd have to say, probably."

Secretary Gates said he believes top Iranian leaders know about the weapons flow to Iraq even though he has not seen definitive proof.

The top U.S. military officer, Admiral Mike Mullen, added "Nor have I (seen definitive proof), although I don't know how they couldn't be (aware)."

The United States has long accused Iran of providing the material for high-powered roadside bombs that can pierce armored vehicles, as well as other weaponry and support for Iraqi Shiite militias. But U.S. officials have declined to say whether senior Iranian leaders are involved in the effort.

Iran denies the charge.

Secretary Gates was also asked about a report in the Los Angeles Times a month ago. The Times quoted the top U.S. general in Iraq, David Petraeus, as saying Iran's president promised Iraq's prime minister he would stop the flow of weapons, training, money and direction to Shiite militias in Iraq. "It is my understanding that they have provided such assurances. I don't know whether to believe them. I'll wait and see," he said.

Secretary Gates said it is too early to determine whether Iran is living up to that promise. Earlier Thursday, the second-ranking American commander in Iraq, Lieutenant General Ray Odierno, expressed a similar view.

"It's unclear yet to me whether they have slowed down bringing in weapons and supporting the insurgency or not. I'll still wait and see. But we still have found some caches. Lately, we have found three or four significant rocket caches, as well as rocket launchers that were fairly new. Again, we don't know when those came into the country exactly," he said.

General Odierno also reports his forces found a large cache of material for the high-powered bombs just a week ago. He also says there has been some decline in violence by Shiite groups in recent months. He attributes that in part to coalition attacks on the groups and their leaders, and to the ceasefire declared by prominent Iraqi Shiite leader Moqtada al-Sadr.