Washington is engaging Iraqi and Kurdish authorities to de-escalate tensions in Kirkuk amid reports of clashes, a U.S. State Department official told The Defense Post on Sunday.

Earlier in the day, Iraqi Prime Minister Haider al-Abadi announced an operation to retake federal installations in Kirkuk, which is largely under the control of Kurdistan Regional Government.

“We are monitoring the situation in Kirkuk closely and are very concerned by reports of a confrontation. We are engaged with all parties in Iraq to de-escalate tension,” the official said. “We support the peaceful exercise of joint GOI [Government of Iraq] – KRG authority in all disputed areas.”

Tensions between Baghdad and Erbil escalated after the Kurdish independence referendum held on September 25. Ninety-two percent of Kurds voted in favor of secession from Iraq, but federal authorities proclaimed the referendum unconstitutional and refused to recognize the results.