The programs are meant to gather intelligence and support the government of Prime Minister Nouri al-Maliki, and include a communications-interception unit on the ground in Iraq, as well as drones operated from a Baghdad airfield.
The head of Iran's paramilitary Quds Force, Gen. Qassim Suleimani, has visited Iraq twice to plan strategy and mobilize members of Shiite militias. In addition, Iranian transport planes make two daily flights to Baghdad, each flight carrying 70 tons of military supplies and equipment, the U.S. officials said.
"It's a substantial amount," said an unidentified official. "It's not necessarily heavy weaponry but it's not just light arms and ammunition."
Iran's actions come with no involvement or coordination with the United States, which has sent 300 military advisers to Iraq. Nothing, thus far, has come of a dialogue between the United States and Iran over Iraq's security breakdown.
"Iran has many different power centers and different elements of Iran are sending different messages and doing different things," a senior State Department official said Sunday. "They are definitely extremely interested in what's happening here, to say the least."
The movement of militants toward Baghdad was a topic of conversation Tuesday, when U.S. Secretary of State John Kerry met in Brussels with NATO foreign ministers to discuss the situation in Ukraine. On Tuesday he consulted with Catherine Ashton, the European Union foreign policy director, to confer on Ukraine and "the grave security situation on the ground in Iraq," State Department spokeswoman Jen Psaki said in a statement.