Early in the ISIS war, Kurdish Peshmerga forces advanced into the city of Kirkuk, after Iraqi military forces fled. The Kurdistan Regional Government (KRG) insisted at the time that they believe Kirkuk was a Kurdish city that should be in their autonomous region.

Over the past week, the KRG’s Peshmerga forces have reportedly been marking a new border on the outskirts of Mosul, saying their involvement in the offensive is over. KRG President Massoud Barzani confirmed that the Kurdish forces will not “retreat” from any territory taking in the war.

The Peshmerga has gained substantial territory across northern Iraq during the ISIS war, including major parts of the Nineveh Province, as well as most of Kirkuk Province. Though the central government doesn’t recognize this takeover as legitimate, the indications are that the KRG considers everything they took annexed into their territory.

There was already considerable tension between Iraq and the KRG before the ISIS war, and the new territorial disputes are likely to add a lot to the tension, setting the stage for an increasingly likely war of secession when the current ISIS war wraps up.