A senior military spokesman says there is clear evidence that Iran has directly aided insurgents in Iraq. Those comments follow Iraq's deadliest month since the U.S.-led invasion, in terms of civilian casualties.

In the Baghdad neighborhood of al Mashtal Thursday, there were the familiar scenes that have become daily reminders of Iraq's insurgency -- burned out cars, wounded rushed to hospitals, and U.S. and Iraqi troops cleaning up the mess after another suicide bombing. One car blast about 100 meters from the al-Rashad police station killed two civilians and injured at least five others.

Sectarian violence in Iraq culminated in nearly 3500 deaths last month, making July the deadliest month there since the U.S.-led invasion in March of 2003.

U.S. and Iraqi officials have accused foreign fighters, especially from Jordan and Syria, of playing a large role in the bloodshed. Now a senior U.S. military official says there is clear evidence that Iran has a direct hand in sectarian violence.

Brigadier General Michael Barbero

Brigadier General Michael Barbero made that accusation to reporters at the Pentagon Wednesday. He said U.S. troops in Iraq have had no direct contact with Iranian fighters. But he says there is a clear link between the violence and Iran.

"Iran is definitely a destabilizing force in Iraq,” he said. “I think it's irrefutable that Iran is responsible for training, funding, and equipping some of these Shia extremist groups and also providing advanced IED technology to them."

General Barbero declined to say what policy the U.S. should adopt to deal with any Iranian connection to Iraq. But he said any military action that neutralizes the nation's Shia extremist groups will go a long way toward eliminating Iran's influence.

"We have a very adaptive, intelligent ruthless enemy, and they will adapt to our measures,” said the general. “And there's a saying at the tactical level -- the enemy has a vote.  Well, the enemy in Iraq has a vote, too, and they're going to adapt, and we have to adapt along with them and we have." 

General Barbero said he is encouraged by the job of Iraqi security forces. He says two-thirds of security in Baghdad is now handled by Iraqi units. But despite what he called positive signs, he would only say he is "cautiously optimistic" about Iraq's progress toward a stable future.