In foreign policy, politics sometimes comes down to necessity. Iran has said it is willing to co-operate with the United States to help Iraq in its fight against radical Sunni insurgents hell-bent on taking Baghdad.
President Hassan Rouhani told state television on Saturday that although Iraq had not asked its Western neighbour for help, it stood ready to provide support "within international law". That aid is most likely to include logistics support and weapons, rather than the ground troops which is the one thing that Iraq sorely needs.
As US President Barack Obama contemplates an American response to the sudden crisis in northern Iraq, whether key towns have been captured by jihadists from the Islamic State of Iraq and the Levant (ISIS).
Iran has sent Major General Qassem Suleimani, a veteran of the feared Iranian revolutionary guards, to Baghdad to discuss the military approach. Iran, the great Shia power, is determined not to see Shia-majority Iraq fall to the Sunni milita.
A senior Iranian official told Reuters that the idea of co-operation with the US is being discussed within the Tehran leadership.
And senior US officials told the Guardian that an air campaign was under serious discussion, possibly targeting ISIS fighters not just in Iraq but in Syria.
Though the number of ISIS fighters in Iraq is believed to be no more than 7,000, they have driven Iraq's ineffectual and divided armed forces out of the second city of Mosul and other key Iraqi towns in the north, and are now within 40 miles of the capital.
The country's top Shia cleric, Grand Ayatollah Ali al-Sistani, used Friday prayers today to call for those "capable of carrying arms" to standing up to the Sunni militants, who took two more towns overnight and reportedly fighting just 50 miles from Baghdad.
Iraq Joins Up
"People who are capable of carrying arms and fighting the terrorists in defence of their country ... should volunteer to join the security forces to achieve this sacred goal," said Sheikh Abdulmehdi al-Karbalai, delivering Sistani's message.
On Iraq's Western border, the masked jihadists of ISIS have been quite literally bulldozing the frontier of a new Islamic state, merging the Iraqi areas they now control with rebel areas in Syria. Governing a significant wedge of Iraq, the militants have created a document that lays out the law in the new Caliphate - including amputations of limbs for stealing, a ban on women leaving their homes, and crucifixion for criminals.
ISIS have announced that they executed 1,700 Shiite soldiers who surrendered in the occupied city of Tikrit, but pardoned 2,500 Sunni troops.
They could also very well have become the world's richest terror organisation after an injection of £250m into their coffers following a raid on Iraq's northern city of Mosul.
Iraqi army troops chant slogans against the Islamic State of Iraq and the Levant (ISIL) as they recruit volunteers
The militant jihadists currently advancing on the Iraqi capital of Baghdad are now rolling in riches, with an armed raid on Mosul's central bank reportedly resulting in a haul of 500 billion Iraqi dinars (£250m).
But to attack the Sunni strongholds in the north would be playing into the hands of ISIS, who have framed the conflict as a sectarian struggle against Shia prime minister Nouri al-Maliki. Civilian casualties could be crucial for ISIS to win the hearts of the people who have come under their rule.
Obama said he would consider over the coming days a "range of other options" drawn up by military chiefs short of sending ground forces back to the country they withdrew from in 2011.
He added: "Any action that we may take to provide assistance to Iraqi security forces has to be joined by a serious and sincere effort by Iraq's leaders to set aside sectarian differences, to promote stability and account for the legitimate interests of all of Iraq's communities and to continue to build the capacity of an effective security force.
"We can't do it for them and in the absence of this type of political effort, short-term military action, including any assistance we might provide, won't succeed.
"So this should be a wake-up call: Iraq's leaders have to demonstrate a willingness to make hard decisions and compromises in order to bring the country together."
Speaking after talks on Iraq with US secretary of state John Kerry in London, Foreign Secretary William Hague said Britain's three priorities were to see Iraqi security services stabilise the situation, for Iraq's leaders to show "a united response to this brutal aggression" and urgent help for those fleeing the violence.