Iraq received the first batch of Sukhoi warplanes from Russia as it pressed a counter-attack on Sunday against a Sunni militant onslaught that threatens to tear the country apart.
Witnesses reported waves of government air strikes Sunday on the city of Tikrit, overrun by the insurgents when they swept across vast areas of north and west Iraq earlier this month.
World leaders, alarmed by the pace of the reverses in Iraq, have meanwhile urged a speeding up of government formation following April's general election, warning that the conflict, driven by sectarian divides, cannot be resolved militarily.
The newly-purchased Su-25 aircraft are expected to be pressed into service as soon as possible, bolstering Iraq's air power as it combats the insurgency that has killed more than 1,000 people and sparked a humanitarian crisis with hundreds of thousands displaced.
An Iraqi official said that pilots from executed dictator Saddam Hussein's air force would fly the planes.
Su-25s are designed for ground attack, meaning they will be useful for Iraqi forces trying to root out militants, led by jihadists from the Islamic State of Iraq and the Levant, from a string of towns and cities they have seized.
Iraqi Prime Minister Nuri al-Maliki on Thursday announced that Baghdad was buying more than a dozen Sukhoi aircraft from Russia in a deal that could be worth up to $500 million (368 million euros).
While Washington has begun sending military advisers to help Iraqi commanders and is flying armed drones over Baghdad, Iraqi officials have voiced frustration that multi-billion dollar deals for US-made F-16s and Apache helicopters have not been expedited.
Iraqi forces have for days been pressing a campaign to retake Saddam's hometown of Tikrit, which fell to the militants on June 11.
- Iraqi air strikes -
On Sunday, Iraqi aircraft carried out strikes in various areas in central Tikrit, and Saddam's palace compound in the city, witnesses said, a clear sign that militants are still holed up in the city.
Thousands of soldiers, backed by tanks and bomb disposal units, have been engaged in the major operation aimed at retaking the city.
According to Maliki's security spokesman, Iraqi forces are coordinating with US advisers in "studying important targets."
Also Sunday, fighters backed by the Kurdish peshmerga force were advancing on the Shiite-majority village of Basheer, south of Kirkuk that was taken over by militants during the offensive, officials said.
Maliki's security spokesman has said hundreds of soldiers have been killed since the insurgent offensive was launched on June 9, while the UN puts the overall death toll at over 1,000, mostly civilians.
The US has pushed for political reconciliation and while it has stopped short of calling for the premier to go, it has left little doubt it feels he has squandered the opportunity to rebuild Iraq since American troops withdrew in late-2011.
US officials have also said a proposed $500-million plan to arm and train moderate rebels in neighbouring Syria could also help Iraq fight ISIL, which operates in both countries.
Russian Deputy Foreign Minister Sergei Ryabkov said on Saturday in Damascus, meanwhile, that Moscow "will not remain passive to the attempts by some groups to spread terrorism in the region."
"The situation is very dangerous in Iraq and the foundations of the Iraqi state are under threat."
- Political reconciliation urged -
Ryabkov, whose country is Syrian President Bashar al-Assad's main backer, did not elaborate on what steps Russia might take.
World leaders have insisted on a political settlement among Iraq's Shiite Arab, Sunni Arab and Kurdish communities and Grand Ayatollah Ali al-Sistani, revered among the country's Shiite majority, has urged political leaders to quickly form a government after parliament convenes on Tuesday.
Maliki, who has publicly focused on a military response to the crisis, has acknowledged that political measures are also necessary, but politicians have nevertheless cautioned that naming a new cabinet could still take a month or more.
Despite unity calls, Iraqi Kurdish leader Massud Barzani has said Baghdad could no longer object to Kurdish self-rule in Kirkuk and other areas from which federal forces withdrew as the insurgents advanced.
Kurdish forces moved into areas vacated by Iraqi federal soldiers, putting them in control of disputed areas that they have long wanted to incorporate into their three-province autonomous region, a move Baghdad strongly opposes.
International agencies have sounded the alarm over the humanitarian consequences of the fighting, with up to 10,000 people having fled a northern Christian town and 1.2 million displaced in Iraq this year.
The International Organisation for Migration warned that aid could not reach tens of thousands of displaced Iraqis, and called for humanitarian corridors.