The government of Iraq announced on Twitter that the Iraqi Army has been ordered to retake land in Kirkuk province that is currently under control of Kurdistan forces:

Yes, the U.S. has armed both sides:

More from the Guardian on why they’re fighting:

Tensions in the area began rising several weeks ago, when the country’s Kurds voted for independence from Baghdad. The referendum was bitterly opposed by Iran, Baghdad and Turkey and has since led to a blockade of the region by all three powers.

This was land abandoned by Iraq in 2014 when they retreated from ISIS. From the Washington Post:

Iraq has demanded that Kurdistan allow its forces to return to positions it held before the war against Islamic State militants. Kurdish forces took control of military bases and oil fields around Kirkuk after Iraqi forces collapsed in the face of the Islamic State’s 2014 advance.

There are early reports of clashes:

Pray for the civilians caught in the middle:

Response from the Pentagon:

Good luck with that.

Update. Iranian General Qassem Soleimani is advising the Iraqis:

The same Soleimani that former general David Petraeus warned about in 2015:

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Editor’s note: This post has been updated.