Russian President Vladimir Putin is due to hold talks with Iraqi Prime Minister Nuri al-Maliki in Moscow on the third and final day of the Iraqi official's visit to Russia.
Discussion are expected to focus on boosting bilateral ties.
Russian media have reported Russia has agreed to sell Iraq arms worth $4.2 billion, including attack helicopters and air-defense systems.
The Mi-28 attack helicopter, and the Pantsir air-defense sytem are considered among Russia's most modern weapons.
Interfax reports the two sides are also in talks on the sale of Russian fighter jets and armored vehicles to the Iraqi Army.
Reacting to the reports, the U.S. State Department said the U.S. military support relationship with Iraq was "very broad and very deep."
Spokeswoman Victoria Nuland said U.S. military sales to Iraq amount to $12.3 billion.
"We're doing some 12.3 billion dollars worth of military business with Iraq," Nuland said. "So, I don't think one needs to be concerned about that relationship being anything but the strongest."
Based on dpa, Interfax and Itar-tass reporting