Foreign forces, small in numbers but militarily potent, are already in Iraq, positioned to shape the outcome of the bloody sectarian war threatening to tear the country apart.
But it's clear that while the U.S., Russia and Iran are willing to commit military personnel, munitions or both to the fight, the three have different and sometimes opposing objectives.
Hundreds of U.S. advisers, most of them Special Forces – officially President Barack Obama has told Congress he has authorized only 770, so far – are in Baghdad and, according to some reports, are already helping with the Iraqi counterattack on Tikrit, Saddam Hussein's hometown, which fell to Sunni insurgents last month.
A handful of Russian Su-25 ground-attack warplanes – called Frogfoots by Western militaries – have also arrived in Iraq. The Baghdad government claims, improbably, they will be flown and maintained by Iraqi air force personnel even though the country hasn't operated a jet fighter since 1991. Most observers assume Russian or eastern European pilots familiar with the aircraft, which has been used in close air support and counterinsurgency missions since the 1980s when the Soviet Union invaded Afghanistan, will be doing the flying at least until Iraqi pilots can be trained.
Iran denies it has any troops or armed forces on Iraqi soil. But an unknown number of elite troops from the Quds Force are widely believed to be there, and the Quds commanding general has been in and out of Baghdad in the past three weeks. Hulking Ilyushin Il-76 military transport planes from Iran are also flying several missions daily to Iraqi airfields, according to eyewitnesses. Each flight could carry up to 70 tonnes of armoured vehicles or munitions or, alternatively, up to 100 combat-equipped troops.
"We have no plans to send troops to Iraq," Hossein Amir-Abdollahian, the Iranian Deputy Foreign Minister said Wednesday. But, he added, Tehran would respond positively to requests from Baghdad. Troops and weapons that "Iraq needs to conduct an effective fight against terrorism will be provided," if they are requested, he said in Moscow.
The Iraq crisis, which could violently dismember a country long riven along sectarian fault lines, has – at least for the moment – put Russia, Iran and the U.S. on the same side of the conflict against the Sunni insurgency.
Tehran wants to back the Shiite-dominated government in Baghdad and stiffen the largely Shia Iraqi army as well as the disparate Shia militias. Keeping the Sunni insurgency from threatening Shia holy shrines, in Karbala and Najaf and retaining its strategic role as the region's Shia power, matter to Tehran. Far less important is whether Iraq remains a single state or disintegrates along sectarian linesinto Kurdistan and two successor Arab states split along the Sunni-Shiite fault line.
As for its behind-the-scenes military involvement, "Iran is likely to be playing somewhat of an overarching command role within the central Iraqi military apparatus," Charles Lister, a visiting fellow at the Brookings Doha Center in Qatar, told The New York Times.
For Moscow, proving it can still project power – especially by responding within days to Baghdad's desperate call for ground-attack aircraft after the Obama administration dithered for years on selling Iraq some F-16s – presents another opportunity for Russian President Vladimir Putin to show some swagger. As in Crimea and more recently in eastern Ukraine, Mr. Putin has enhanced his popularity at home by reasserting Russia as a power abroad. In the Middle East, first by backing Syrian dictator Bashar al-Assad and now by sending Iraqi Prime Minister Nouri al-Maliki the jets he wanted, Moscow is manoeuvring for influence more than actually making a military difference.
Washington remains cautious, even as the quite potent U.S. military buildup continues.
The Pentagon is sending Iraq an emergency supply of up to 4,000 Hellfire missiles, which can be fired from helicopter gunships or Predator and Reaper drones, according to reports in Washington. And while U.S. President Barack Obama has ruled out sending sizable numbers of U.S. combat forces back to Iraq and conditioned military aid on the creation of an inclusive government in Baghdad, already U.S. warplanes are flying dozens of reconnaissance missions daily from the aircraft carrier U.S.S. George H. W. Bush.
Small unarmed U.S. drones are also reported to be flying from base stations around the Iraqi capital, likely gathering intelligence on the Sunni forces, led by Islamic extremists that had seized much of northern and western Iraq in a lightning advance over the past two months. And some U.S. Apache helicopter gunships have been airlifted in huge military cargo aircraft to Baghdad, Pentagon spokesman Rear Admiral John Kirby said.
Although the insurgent advance has reached to the outskirts of Baghdad to the west and within 70 kilometres to the north, the capital isn't currently under attack.
In Rear Adm. Kirby's view, "the threat continues to be very real."
The Apaches, coupled with U.S. Special Forces on the ground, provide a fearsome air support capacity that could help stall the insurgent advance while Baghdad attempts to mobilize a credible ground-fighting force after mostly Shia divisions in the north collapsed and fled in disarray, surrendering Mosul, Tikrit and other key cities to the insurgents.
Ben Rhodes, the President's deputy national security adviser, said U.S. air strikes – against the Sunni extremists such as the Islamic State in Iraq and the Levant – could be ordered if Mr. Obama decides "ISIL is posing a threat to U.S. interests that would necessitate our taking action against them, as we have against terrorist organizations in other parts of the region."
That opens the door to unilateral U.S. military action even if a moderate, inclusive new government doesn't emerge in Baghdad because the trigger would be to defend U.S. interests rather than shore up one side in a sectarian war.