Ryan Crocker was ambassador to Iraq from 2007 to 2009. He is the Kissinger Senior Fellow at Yale University’s Jackson Institute.

The situation in Iraq has taken a very dangerous turn. Events there in recent days are reminiscent of those that led to virtual civil war in 2006 and resulted in the need for a surge in U.S. troop levels, a new strategy and very heavy fighting. Indeed, the places where the violence has erupted are eerily familiar, as many were strongholds of al-Qaeda in Iraq at the outset of the surge, before the spread of the Awakening movement that fostered reconciliation between disaffected Sunni Arabs and the Shiite-led government in Baghdad. The recent events come on top of increasing incidents of horrific attacks by al-Qaeda in Iraq, with last month seeing the largest losses in years — and they take place against a backdrop of increasingly serious political discord. These developments clearly require the attention and support of the international community, led by the United States.

Progress toward political accord and pluralism first came to Iraq in 2007 and 2008 when, as security spread during the surge, Sunni and Shiite leaders opted to resolve their differences through accommodation rather than through violence. Their commitment survived the difficult aftermath of the 2010 parliamentary elections, in which no one party won a clear mandate. It survived last year’s arrest of the bodyguards of Sunni Vice President Tariq al-Hashimi on charges of terrorism, as well as his subsequent trial in absentia and death sentence.

And although domestic political issues galvanized Sunni areas of the country over the past four months, both the Iraqi Security Forces and the protesters exercised considerable restraint. Sunni leaders took concrete steps to keep demonstrations peaceful by searching protesters for weapons. Even after eight Sunni protesters were killed in Fallujah in January, both sides managed to de-escalate.

That all changed last week. It began in the town of Hawija, near Kirkuk, where Iraqi Security Forces said Sunni protesters were harboring insurgents who had killed soldiers at a government checkpoint. The protesters denied there were any insurgents in their camp and failed to turn over any individuals. On April 23, the security forces launched an action in the camp — and a violent clash ensued, leaving scores dead and injured. Now Sunni Arab sheikhs who had been urging restraint are calling for war. Some reports say that the tribes are gathering former insurgents and preparing to fight. Violent incidents have already taken place, with more than 40 people killed in one day in Mosul alone.

This has the gravest implications for Iraq’s security and stability. Al-Qaeda in Iraq has already begun to reestablish itself in areas that Iraqi and U.S. forces cleared at enormous cost over the past five years. And Jabhat al-Nusra, al-Qaeda in Iraq’s front group in Syria, is attempting to hijack the secular resistance to Syrian President Bashar al­Assad. These developments threaten not only to unravel the gains made since 2007, but also to energize the forces of violent extremism in the heart of the Arab world, already burning in Syria.

The country’s leaders need to de-escalate the crisis and address the concerns of those who are aggrieved. One new grievance in particular, the delay in provincial elections in Anbar and Ninewah Provinces, must be addressed rapidly. Most of Iraq voted for provincial leaders on April 20th, but security issues delayed the vote in Anbar and Ninewah until May 18, and then until July 4 — exacerbating the sense of sectarian marginalization. It is important that those elections go forward as scheduled.

The protests have not just been about the electoral delay. Protesters also demand significant reforms to Iraqi detention policies and the manner in which de-Baathification laws are implemented. We note that Prime Minister Nouri al-Maliki has offered concessions on the latter issue, and we look forward to support from other political parties with Shiite constituencies. Above all, it is imperative for the Iraqi people and their leaders to recall the commitment they made in 2007 to reject sectarian violence and to press forward to build a better Iraq for all Iraqis.

It is also incumbent on the friends of Iraq to support this effort. Progress in Iraq came when coalition elements encouraged Sunni communities to work with a government in which they still lacked trust. It is vital that the spirit that animated the progress then be reinvigorated now. It has thus been good to read of the activities in recent days of the U.S. ambassador in Baghdad and the U.N. mission there, calling for calm, engaging with all parties and reminding them of what they could lose: the new Iraq that they and we paid so much to create.

Though the United States has withdrawn its troops from Iraq, it retains significant leverage there. Iraqi forces were equipped and trained by Americans, and the country’s leaders need and expect our help. Secretary of State John F. Kerry showed great initiative in making Iraq part of his first visit abroad; he should return to signal Iraq’s long-term importance to the United States and to regional stability, and he should engage all of Iraq’s leaders. Another step would be convening a secretarial-level meeting of the joint commission established under the Strategic Framework Agreement.

To be clear: For Iraqis to pull back from the brink, the United States must lead a sustained, high-level diplomatic effort. We have done so successfully in the past, beginning in 2007; we must do so again. The stakes for Iraq and the region are far too high for anything less.

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