Iraq has received five used Sukhoi-24 fighters and advisers from Russia even as ISIS militants declared an independent caliphate (Islamic state) out of the occupied territories.
Isis has proclaimed the creation of an Islamic state of the regions it controls in Iraq and Syria.
The declaration comes at a time when Iraq has stepped-up its offensive to take back the city of Tikrit in the northern part of the country.
The supply of Sukhoi combat aircraft by Russia took place after the promised deliveries of fighter jets from the US were being delayed.
Iraq Prime Minister earlier told BBC that faster deliveries from the US could have controlled the insurgency.
The country has sought 25 Sukhoi jets from Russia and Belarus in deals reportedly worth $500m.
Iraq Ministry of Defence told BBC that the deal with Russia was aimed at increasing the firepower of the air force and the rest of the armed forces in order to fight terrorism.
The Russian advisers are currently assembling the jets, which are likely to be operational in three to four days.
Meanwhile, the American military advisers are assisting Iraq with inputs in the Tikrit battle.
The US has confirmed the use of armed drones in the region to protect its personnel but denied that the 300 advisers it sent last week are directly participating in the offensive.