KIRKUK, Iraq — After weeks of threats and posturing, the Iraqi government carried out a military assault on Monday to curb the independence drive by the nation’s Kurdish minority, wresting oil fields and a contested city from separatists pushing to break away from Iraq.

The deadly clashes pitted two crucial American allies against each other, with government forces seizing Kirkuk from Kurds who had intended to build a separate nation in the northern third of Iraq.

The Kurds voted overwhelmingly for independence from Iraq in a referendum three weeks ago. The United States, Baghdad and most countries in the region had condemned the vote, fearing it would fuel ethnic divisions, lead to the breakup of Iraq and hobble the fight against the Islamic State.



Iraqi government troops and the Kurdish forces, known as pesh merga, are both essential elements of the American-led coalition battling the Islamic State, also known as ISIS or ISIL. Both forces are supplied and trained by the United States.