The US has sent Hellfire air-to-ground missiles to Iraq's air forces, which is using them in its campaign against the country's branch of al Qaida.
Two Iraqi intelligence officers and a military officer said that 75 Hellfires arrived on December 19 and more will be shipped in the future.
They said the missiles are being used now by four Iraqi King Air propeller planes during a large-scale military operation in the western desert near the borders with Syria.
An intelligence official said that the missiles were proven "successful" and were used to destroy four militant camps.
US state department spokeswoman Jen Psaki confirmed yesterday the missile shipment and also said that the United States was planning on sending ScanEagle drones.
"The United States is committed to supporting Iraq in its fight against terrorism through the Strategic Framework Agreement," she said, referring to a 2008 pact between the two nations.
"The recent delivery of Hellfire missiles and an upcoming delivery of ScanEagles are standard foreign military sales cases that we have with Iraq to strengthen their capabilities to combat this threat."
Hellfires are widely used by US forces in their campaign against al Qaida, often targeting militant hideouts or vehicles.
Iraq launched its operation in the largely desert province of Anbar followed the weekend killing of a senior military commander, a colonel and five soldiers in an ambush.
Al Qaida is believed to have made use of the war in Syria, which borders Anbar, to rebuild its organisation in Iraq. Hardline fighters are believed to shuttle between the two countries.
According to United Nations estimates, more than 8,000 people have been killed since the start of the year in Iraq.
Also yesterday, a salvo of rockets hit a camp that houses members of an Iranian opposition group that is at odds with the government in Baghdad.
The Paris-based National Council of Resistance of Iran said in an emailed message that "dozens" of rockets killed two of its members in the attack on Camp Liberty near Baghdad Airport. It said others were wounded.
An Iraqi security official said four rockets hit the camp and that two people were wounded, none killed. It said three more rockets hit a nearby Iraqi military camp without causing damage.
The group, which is strongly opposed to Tehran's clerical regime, was welcomed into Iraq by Saddam Hussein in the 1980s during the war with neighbouring Iran.
Their fortunes turned sharply with the Iraqi dictator's toppling in the 2003 US-led invasion. Iraq's current Shiite-led government, which has strengthened ties with Tehran, considers their presence in the country illegal.
Meanwhile, a bomb attached to a bus killed three civilians and wounded six in the southern Baghdad neighbourhood of Jisr Diala, a security and a medical source said.