The Pentagon assessed progress in Iraq from September to November in its quarterly report to Congress, issued on Tuesday.
Iran "continues to reflect a fundamental desire to oppose the development of a fully secure and stable Iraq," despite its "persistent promises to the contrary," the report said.
Iran tried to undermine the U.S.-Iraqi security agreement forged last year, the report said, and "continues to host, train, fund, arm, and direct militant groups intent on destabilizing Iraq."
"Countering malign influence and balancing soft Iranian influence remain priorities to stabilize Iraq and ensure the sovereignty of its people," the report said.
The report cites improvements in politics, security, economics, diplomacy and rule of law, but emphasizes their fragility.
"Iraq remains fragile because its major power brokers do not share a unified national vision. They disagree on the nature of the state and are reluctant to share power and resources," it says.
"The overall security situation in Iraq continues to improve," the Pentagon report says, crediting, among other things, improved Iraqi security forces and the political will of the government to fight militants. It says the insurgency has diminished as some militants embrace the Iraqi government.
The U.S.-led coalition has transferred security leadership to Iraqi forces in several provinces and coalition troops from many countries have withdrawn their forces. The United States and Iraq have signed a bilateral security agreement calling for all U.S. troops to leave by the end of 2011.
Although the number of civilians killed has dropped, assassinations of juridical and legislative officials have increased and violence against Christians in Nineveh province has stirred concern.
The report raises fears that the mishandling of key political efforts in the country could reverse gains.
Crucial efforts include the upcoming provincial elections, resolving disputes over areas such as Kirkuk city; resettling displaced people; and providing permanent employment for the Sons of Iraq, the largely Sunni U.S.-backed security personnel.
