Few could have predicted how quickly the security crisis in Iraq would escalate before 10 June, when Islamist militants seized control of the country’s second-largest city of Mosul.

The Iraqi government had officially asked the US to stage air attacks to halt the Islamic State in Iraq and Syria’s (Isis) advance on Baghdad.

US President Barack Obama has told Congressional leaders he does not need approval from the US legislature for any action in Iraq, but he is still weighing his options for intervention in the crisis.

The request for Washington’s assistance just two and a half years after the last US forces left the country illustrates how badly Prime Minister Nouri al-Maliki has failed in creating unity among the fragile religious and ethnic divisions.

While the extent of Isis’ military success in northern Iraq appears to have caught Baghdad off guard, the Islamist militants have controlled the cities of Fallujah and Ramadi in the Anbar province since the start of the year.

In the run-up to the 30 April election, Al-Maliki was widely criticised for his inability to deal with the security situation in the western province, which has a significant Sunni majority. The attacks could not have come at a worse time for the premier. Although his State of Law coalition emerged from the polls with the most seats of any party, his lack of control over vast areas of the country has weakened his mandate to lead for another four-year term.

The situation has played into the hands of the Kurdistan Regional Government (KRG), which was quick to claim the city of Kirkuk as Iraqi security forces fled from militants. The Kurds have been vocal in their criticism of Al-Maliki and are unlikely to back him for a third term without significant concessions to the KRG, which is now independently exporting oil despite criticism from Baghdad.

Sectarian violence has now hit a post-war high in Iraq, and it seems Al-Maliki could not be more ill-equipped to tackle the situation.