On Monday, Turkish president Recep Tayyip Erdogan responded to news of an Iraqi Kurdish independence referendum by threatening to cut off Kurdish oil exports through Turkey's ports. “We have the tap. The moment we close the tap, then it’s done," Erdogan threatened. The vote has not yet been counted, but the referendum is widely expected to pass.
Turkey is engaged in a long-running conflict with its own Kurdish minority, and it has no desire to see a formally independent Iraqi Kurdistan on its borders. Iraq's Kurdish enclave is a semi-autonomous state with its own government and military, but it is technically administered by Baghdad.
Iran and Iraq have also expressed strong opposition to the prospect of a Kurdish nation, but of the enclave's neighbors, Turkey may have the most leverage: the landlocked Kurdish Regional Government has no seaports to export its plentiful supply of oil, its primary source of revenue, so it ships hundreds of thousands of barrels per day by pipeline to the Turkish port of Ceyhan.
"Let's see where the regional government will flow its oil, through which channels and where it will sell it," said Erdogan. He added a thinly veiled threat - "we may arrive one night, suddenly," a reference to a Turkish military raid into Syria last year.
Iraq and Turkey are conducting a joint military drill on the Turkish side of the border with the region, and Iran has announced its own exercises in its border region. Any military intervention could devolve into a more serious conflict: the Kurdish Regional Government has a well-trained standing army, an effective military force that is a key American partner in the fight against ISIS. The U.S. government provided Iraqi Kurdish military forces with nearly $480 million in aid in FY2017, and in May, President Donald Trump authorized the Defense Department to equip Syrian Kurdish forces to fight Islamic State militants – despite Turkey’s objections. U.S. officials have called for the Kurdish Regional Government to cancel the independence referendum, arguing that it could destabilize relations in the Middle East and distract from the campaign against Islamic State.