Masoud Barzani, president of the Iraqi Kurdistan region, made a major Twitter announcement earlier today: The region will hold an independence referendum on Sept. 25.

It's big news, but not surprising — Iraqi Kurds have long sought independence from the rest of Iraq. And in recent months, Barzani has told various officials he would push for a referendum.

Yet timing is everything. With Mosul soon to fall to Iraqi forces, and Kurdish forces playing an instrumental combat role against the Islamic State, Barzani believes he now has the political capital to act.

While the United States might be tempted to give reflexive support to Kurdish aspirations, our diplomats must be cautious. The referendum sets Kurdistan on a collision course with Iraq, Iran and Turkey.

In the case of Iraq, the challenge is simple: Iraq doesn't want to lose vast areas of territory. That said, Prime Minister Haider al-Abadi is in a bind. He needs the help of Kurdish forces to continue fighting the Islamic State, and his position in Baghdad is tenuous.

As I've explained, Iran is seeking to restrain al-Abadi as he forges greater cooperation between various Iraqi political blocs, including Kurdish parties. But Abadi also knows that Sunni Arabs living alongside Kurds in northern cities like Mosul and Kirkuk will resist losing what they regard as natural Iraqi territory.

Meanwhile, the Iranian government has maintained generally positive relations with Kurdish political entities and it greatly values stability along its western border with Iraq. That mountainous region already enables some Kurdish groups to skirmish with Iranian forces. And on its side of the border, Iran faces a small but potent domestic Kurdish insurgent group.

Were Iraqi Kurdistan to become independent, Iran fears it would empower similar separatism in Iran.

Still, what makes Iran's opposition to Kurdish independence especially concerning is its military capacity. At present, tens of thousands of well-equipped, well-trained Iranian-aligned fighters are operating in northern Iraq. On paper, they serve under the Iraqi security establishment in order to fight the Islamic State.

But that's a pretense. The reality is that these "popular mobilization forces" are in Iraq to give Iran influence over Baghdad. And they answer to the Iranian Revolutionary Guard Corps. If ordered to create havoc in Iraqi-Kurdish territory, they would do so.

Finally, there's Turkey.

This is the big one. Turkey is obsessive in opposing a Kurdish state, and it has good reasons for doing so.

For one, the anti-Turkish PKK terrorist group dominates the armed groups operating in northern Syria. If a Kurdish state is forged from Iraq, the Turks rightly assume that it would appropriate Kurdish-occupied territory in Syria. That would formalize a major security threat along Turkey's border.

But that's not all. In equal measure, Turkey fears a Kurdish state would destabilize its southeastern provinces. Millions of Turkish Kurds live in this area. And tensions between these provincial citizens and President Recep Tayyip Erdogan's government are rising. Enveloping Turkey's main Kurdish political party into his "coup plotter" crackdown, Erdogan's thuggery is fueling Kurdish extremism. If the spark is lit in Iraq, it may quickly spill into Turkey.

Ultimately, the U.S. will have to mediate the above concerns if chaos is to be avoided. We must persuade Turkey and Iran that the Kurds would not use their new state as expansionist launchpad. We must convince the Kurds that our support requires their commitment to placating the aforementioned concerns. We must consolidate al-Abadi's government in Baghdad. And Turkey and Iran must understand that we will not tolerate an invasion of Kurdistan.

Absent U.S. leadership, great bloodletting beckons.