The Islamic State group gloated over the recent U.S. killing of a senior Iranian general, who rose to prominence by advising forces fighting the extremists.
In the first IS comments since Gen. Qassem Soleimani's slaying, the group said his death "pleased the hearts of believers." The editorial was released in the group's al-Nabaa online newspaper late Thursday.
Although the U.S. and Iran strictly avoided working together directly, they were once on the same side in the fight against IS. Neither side wants to see the extremists stage a comeback.
But as the various players in Iraq jockey to come out ahead in a post-Soleimani landscape, Islamic State militants may find an opening. Thousands of fighters are scattered among the group's sleeper cells, and have claimed attacks in both Iraq and neighboring Syria in recent months.
As the head of Iran's elite Quds Force, Soleimani was one of the main commanders on the ground spearheading the fight against IS. He sent thousands of Iran-backed fighters to Iraq and Syria to battle the extremists, and directed Iraqi Shiite militias as well. A top Iraqi militia commander was killed alongside Soleimani in last week's U.S. drone strike.
The IS editorial said that its members tried for years to kill the two commanders, but that "God brought their end at the hands of their allies." It said both men "have gone too far in shedding the blood of Muslims in Iraq and Syria."
Iraq's caretaker prime minister has now asked Washington to start working out a road map for withdrawing the more than 5,000 American troops in Iraq, in response to Soleimani's killing. But the U.S. State Department on Friday bluntly rejected the request.
Iraqis have felt furious and helpless at being caught in the middle of fighting between Baghdad's two closest allies.