Suspected insurgents detonated explosives at the North Oil Company (NOC)-operated Bai Hassan oil field and on a key electricity transmission line from Erbil to Kirkuk on Sunday, the latest in a string of escalating acts of violence across northern Iraq. The attacks on energy infrastructure and security force checkpoints are a near-daily occurrence in areas that were once the frontlines of the war against the self-proclaimed Islamic State (IS) group, which security officials say is still exploited in part due to gaps in coordination between federal Iraqi or Kurdish security forces.