Violence is down 55 percent in Iraq since a U.S.-Iraqi security operation began this summer, U.S. officials said Sunday.
The officials cautioned it was too early to credit Tehran with the recent lull in overall violence, despite recent optimism that Iran was stemming its support for Shiite militia fighters.
"It's unclear to us what role the Iranians might have had in these developments, if any," said Philip Reeker, a spokesman for the U.S. Embassy in Baghdad, at a news conference in the U.S. guarded Green Zone.
"It's difficult to read trends in reductions," he said. "To draw direct lines from that data to say that there are fewer attacks and conclude that there's a particular reason for it. Vis-a-vis Iran's action, that is something we're not yet prepared to do."
Washington has accused Iran of training, arming and funding Shiite extremists inside Iraq. But in recent weeks, U.S. officials have said Tehran appears to have halted the flow of arms across its border into Iraq.
Overall, attacks in Iraq have fallen 55 percent since nearly 30,000 additional U.S. reinforcements arrived in Iraq by June, said Rear Adm. Gregory Smith, a U.S. military spokesman. Some areas are at their lowest levels of violence since the summer of 2005, he said.
Iraqi civilian casualties are down 60 percent across the country since June, and the figure for Baghdad was even better - 75 percent, Smith said.