Isis advance threatens Iraq's very future, claims John Kerry

Iraq's "very future" will be determined in the coming days, the most senior US diplomat, John Kerry, said on Monday as he urged the country's feuding leaders to form a government and confront the jihadist surge currently splintering the country.

Promising "intense and sustained" support to Iraq, the secretary of state said the crisis was "a moment of decision for Iraq's leaders and ... a moment of great urgency." Kerry said that each of the three officials he met, prime minister Nour al-Maliki, parliamentary speaker Osama Nujaifi and prominent Shia leader, Ammar Hakim, had committed to nominating leaders by 1 July.

With the jihadist group Isis now in control of an 800km stretch of the border between Iraq and Syria, and advancing towards the country's most strategic areas, Kerry said: "The very future of Iraq depends on choices that will be made in the next days and weeks. "Not next week, not next month, but now."

Iraq's army again folded over the weekend in the face of the insurgent threat, pushing into the border areas. It has now yielded most of western Iraq to Isis. The capitulation renews pressure on Maliki, who is also commander in chief. But Kerry was careful to avoid directly criticising the beleagured leader, who has seen more than one third of the country slip from his control in less than two weeks. "No country has the right to choose Iraq's leaders for them," he said.

Maliki faces a tough task to assemble a coalition from Iraq's disparate groups, whose enduring divisions make nation building fraught, even now. The large, expensive army he leads has repeatedly cracked under the jihadist threat, exposing sectarian fault lines across Iraqi society – which many claim had been widened by Maliki's refusal to empower the country's Sunnis.

Maliki has pleaded with Washington for US military support, acknowledging that Iraq does not have the means to tackle Isis, which has pledged to oust Iraq's Shia power base and end the country as a unitary state. Kerry, and President Barack Obama had been urging unity over the past week, and appeared to condition airstrikes on Iraqi leaders first finding a consensus. Kerry's comments in Baghdad suggest that political compromise – and military action – are both now fast drawing near.

The US has already deployed two aircraft carriers to the northern Gulf and has sent special forces troops to Iraq – some of whom will act as forward spotters for airstrikes.

Ahead of meeting Kerry, Nujaifi told the Guardian that only the implementation of a federal system of government could hold Iraq together.

"A federal system is a solution," said Nujaifi, who hails from Mosul – the first city to be over-run by Isis earlier this month. "It is constitutional and even the Shias are starting to come around to it. There will be autonomy within each federal state, but Baghdad will remain the central Government.

A federal form of government has regularly been touted as a solution for Iraq over recent years. But such a system would be strongly opposed by neighbouring states, including Syria and Turkey, who fear the implications of such a move for their borders.

"This is a catastrophe. We are at the edge of the cliff and we have to hurry to find a solution," Nujaifi said "We'd been telling the US what was happening here, but they didn't get the message. I have been telling them for years that there is a leader (Maliki) that is sectarian, a one-man band who listens to no-one else. Now they understand."

The jihadists have advanced from Anbar province in the west to the Haditha dam in central Iraq, which is the epicentre of the country's electricity grid. Iraqi reinforcements have been rushed to the area and the dam appears to be at no immediate risk of falling. However Isis has continued to outthink and outmanouvere the Iraqi military, despite its vastly inferior numbers.

Some Isis cells are now on the eastern outskirts of Baghdad. However the capital would be heavily defended if it was attacked and strong doubts remain about the ability of the jihadists to enter the city and secure ground.

"I don't think they need to take Baghdad anyway," Nujaifi told the Guardian. "It is not so important to them given what else they could get their hands on, which would do just as much damage."

Isis was thought to have around 6,000 members before it seized Mosul and Tikrit, but is believed to have recruited heavily over the past week. Foreign fighters who had been based in Syria have also crossed the border to aid with the Iraq push. Several hundred freed prisoners, many of them jailed for terror offences, have also joined their ranks.

The group has made a series of stunning gains, meeting little opposition as it pushed through Anbar and south from Mosul. Shia militias have mobilised in large numbers in the centre and south of the country and the crisis is taking on an ever hardening sectarian feel.

In Washington, the Obama administration said it had reached an agreement with the Maliki government that the 300 military advisers being sent to Iraq would be immune from prosecution.

"We can confirm that Iraq has provided acceptable assurances on the issue of protections for these personnel via the exchange of diplomatic notes."

In 2011, Obama refused to leave a residual force in Iraq without an act of parliament in the country guaranteeing immunity of prosecution to US troops. There is still no such agreement in place, but the White House spokesman Josh Earnest said the administration said the current, far smaller deployment was taking place in a different context.

"We're dealing with an emergency and there is an urgent need for these advisers to do their work on the ground in Iraq," he said. He also said that the Maliki government, which in 2011 was reluctant to see US troops remain in the country, was now "urging" military engagement.