The situation is urgent.

Iranian-backed forces deployed to the Kirkuk front-line overnight. Militias include the Badr Brigade, Khorasan and Tafoof units, as well the notorious Asa’ib Ahl al-Haq, wearing police uniforms. They have been joined by members of the Iraqi Federal Police, Anti-Terror troops, and members of the 9th Division’s Armor Brigade.

Today, Prime Minister Heider al-Abadi delivered an ultimatum to the Patriotic Union of Kurdistan. The ultimatum demands that the Kurds:

– Hand-over control of the Kirkuk airport.

– Relinquish the K-1 air base, also known as Kaywan.

– Surrender all oil fields in Kirkuk province.

– Allow the return of the Iraqi army to all places where they were stationed before ISIS invaded in 2014.

– Remove Kirkuk Governor Najmaldin Karim from his position.

The six-point ultimatum includes a deadline of early Sunday morning. Abadi threatens to attack if the Kurds do not comply.

Prime Minister Nechirvan Barzani of the Kurdistan Regional Government (KRG) has called for calm. “All standing issues should be dealt with through negotiations and peaceful means,” said Barzani. “Our calls for dialogue and negotiations must not be answered with threats, amassing forces and preparations for war.”

But Kurds are preparing for the worst. About 6,000 peshmerga – “those who stand before death” – are being rushed to the front-line, strengthening the line of defense should fighting erupt by design or by accident.

The situation is extremely volatile. Abadi does not control the myriad of militias deploying to Kirkuk. Their backers in Iran could try to provoke hostilities. An incident could cause a spiral of deadly violence, leading to full-bore war.

A buffer zone would keep the sides apart. In parallel, the U.S. needs to play a mediation role.

Brett McGurk, the Special Presidential Envoy for the Global Coalition to Counter ISIS, is the architect of America’s policy in the region, which supports Baghdad and favors Iran. Someone with more credibility, objectivity, and gravitas is needed to mediate.

Washington should stand by its friends, rather than placate its adversaries. The United States and the KRG have cooperated seamlessly since 1991. Beginning in 2014, U.S. military assistance was invaluable to the peshmerga who prevented ISIS from overrunning Iraq. Peshmerga paid a heavy price. More than 2,000 died fighting ISIS.

Kurds and Americans share values as well as strategic interests. Thousands of U.S. service men and women have died or been injured in Iraq. However, not a single American soldier has died in Iraqi Kurdistan over almost three decades.

According to House Resolution 534, introduced by Congressman Trent Franks (R-AZ), “The people of the Kurdistan Region of Iraq have a right to determine their status as a sovereign country. [They] meet the criteria for self-determination…and state recognition.”

The Trump administration faces a clear choice: Support the government of Iraq, which is a proxy for Iran, or stand by the Iraqi Kurds, who are stalwart allies and profoundly pro-American.

Not only can the United States help prevent the current showdown from escalating into war. Only the U.S. has the clout to negotiate a friendly divorce between Iraqi Kurdistan and Baghdad, ensuring U.S. interests as well as peace and stability in the region.

David L. Phillips is Director of the Program on Peace-building and Rights at Columbia University’s Institute for the Study of Human Rights. He served as a Senior Adviser and Foreign Affairs Expert to the State Department during the administrations of President Clinton, Bush, and Obama. He is author of several books on the Middle East including Losing Iraq: Inside the Post-War Reconstruction Fiasco and The Kurdish Spring: A New Map for the Middle East.