Baghdad ? The U.S. military on Friday released nine Iranian citizens, including two described as diplomats, who had been held in American custody in Iraq for as long as three years.

U.S. military officials said the men were no longer considered a threat, but they did not elaborate. Iraqi officials said that they did not have access to the men while they were in U.S. custody to judge independently their innocence or guilt but hoped the move would allow for more dialogue between Iran and the United States.

“Reducing this tension between Americans and Iranians is for the benefit of Iraq,” said Ali al-Adeeb, a Shiite legislator from Prime Minister Nouri al-Maliki’s Dawa party. “Definitely this will help.”

The Iranians were suspected by U.S. officials of being members of the Quds Force, an arm of Iran’s Revolutionary Guard Corps. Their detention has been one of several points of dispute between the two countries. The U.S. military has repeatedly said that the Revolutionary Guard is involved in providing weapons and training for Shiite militias in Iraq. Although Iranian officials have denied those allegations, the U.S. military also says Iran has promised to crack down on any cross-border support to militants.

The U.S. military is expanding its efforts to stop weapons coming over the border from Iran. A new U.S. military outpost under construction less than five miles from the Iranian border is scheduled to be completed next week. At the Zurbatia border crossing in that province, more than 1,000 people and hundreds of vehicles pass into Iraq each day with relatively little oversight. Iran has recently agreed to create a neutral site at the border crossing so guards from both countries can work together to search the cargo.

“Up until the last six months, we did not have the ability to search trucks,” said Col. Mark Mueller, the leader of the U.S. military unit working with Iraqi border guards in Wasit province. “We’re making a lot of headway in those areas, but it’s big. It’s not going to be solved overnight.”