The Pentagon warned Islamic State leader Abu Bakr al-Baghdadi that he will eventually "taste justice" as the US military continues to target the jihadist group's upper ranks.
"We are hunting him, and we will find him," military spokesman Colonel Steve Warren said.
"Just like we found his mentor, [Abu Musab] al-Zarqawi and killed him. Just like we found the grand master of terrorism, Osama bin Laden, we killed him. We are going to find Baghdadi, and he will taste justice."
Warren's prediction comes after the US-led coalition has targeted several senior IS leaders in Iraq and Syria in recent weeks, including Abd ar-Rahman Mustafa al-Qaduli — also known as Haji Imam — who was second-in-command of the extremist group.
"I don't know if that justice will look like a Hellfire missile, or if it will look like a dark prison cell somewhere, but he will find justice one day," Warren said of Baghdadi.
The US Justice Department had offered a bounty of up to US$7 million for information leading to Qaduli. He had been seen as an eventual successor to Baghdadi, for whom a $10 million reward has been offered.
Warren said Baghdadi spends his time in both Iraq and Syria, where the IS group seized large areas of territory in 2014.
Pentagon chief Ashton Carter last week said the military was "systematically eliminating" the IS group's leadership.
Omar al-Shishani, the man known as "Omar the Chechen," who was effectively IS's defense minister, was also killed last month.