A top U.S. military official has blamed Iranian training for an increase in the accuracy of indirect-fire attacks on the heavily fortified Green Zone in Baghdad.

Mortar and rocket fire targeting the area — which houses key military and political headquarters — has increased over the past three months, with the number of casualties also increasing since earlier in the year.

“We have seen in the last three months a significant improvement in the capability of mortarmen and rocketeers to provide accurate fires into the Green Zone and other places, and we think this is directly related to training that is conducted in Iran,” Lt. Gen. Raymond Odierno, the day-to-day commander of U.S. troops in Iraq, said Thursday at a Baghdad news conference.

“So we continue to go after these networks with the Iraqi security forces.”

In recent weeks, U.S. officials have become increasingly public in detailing Iran’s alleged involvement in financing, arming and training insurgent groups in Iraq.

The allegations were repeated during a meeting of the U.S. ambassador in Iraq and his Iranian counterpart earlier this week; Iran has denied the accusations.

Most of the rocket attacks come from largely Shiite districts of Baghdad, military officials have said.

Those areas are home to the Mahdi Army militia, loyal to radical cleric Muqtada al-Sadr. U.S. officials have said that al-Sadr spent several months in Iran after the “surge” began earlier this year. Al-Sadr’s aides have denied that.

And, Iran long has been accused of providing training and materials for “explosively formed projectiles,” a particularly deadly kind of roadside bomb that can pierce armor.

“One of the reasons why we’re sitting down with the Iranian government … is trying to solve some of these problems,” Odierno said at the news conference.

The latest large-scale attack came July 10, when more than a dozen projectiles struck the Green Zone, killing at least three people and wounding 18 others.

In May, the United Nations reported that indirect-fire attacks had become “increasingly accurate,” and reported that at least 26 people died in indirect-fire attacks on the Green Zone between Feb. 19 and June 12.

The number of such attacks also spiked, going from 17 in March to 30 in April to 39 through the first three weeks of May.

Also on Thursday, the U.S. military released a statement denouncing bomb attacks on Wednesday that killed dozens of Iraqis celebrating their national team’s soccer victory in the semifinals of the Asian Cup.

“We join with the citizens of Iraq in expressing outrage against the barbaric attacks on innocent people celebrating their nation’s hard-earned soccer victory,” the statement read.

“This barbarism is a direct attack on the national unity of Iraq and exposes these terrorists for what they really are.”

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