A U.S.-led coalition airstrike hits an Islamic State position near the town of Hole in Syria. (John Moore/Getty Images)

The United States has been eliminating a mid- to high-level Islamic State figure every two days, on average, contributing to President Obama’s decision to send a new Special Operations force to Iraq to intensify efforts to locate and kill militant leaders there and in Syria, a senior administration official said Thursday.

The official described the mission of the force as self-
expanding — more raids on Islamic State sites will garner more intelligence leading to more sites. “The more intelligence we get, the closer we’ll get to these guys,” said the official, who briefed reporters on the condition of anonymity set by the White House.

In testimony earlier this week, Defense Secretary Ashton B. Carter said that key militant figures “removed from the battlefield” in recent months included the Islamic State’s second in command in Iraq, Haji Mutazz; and British-born militants Junaid Hussain and the executioner known as Jihadi John, both reportedly killed in airstrikes in Syria.

The template for the new ground operations, officials have said, was the raid inside Syria in May in which Abu Sayyaf, a key Islamic State commander, was killed and voluminous intelligence was seized on the militant group’s economic structure.

The briefing was part of an administration effort to project coherence and a sense of momentum on a strategy that is often criticized as lacking both.

Map: What a year of Islamic State terror looks like

Overall, the official described significant progress in degrading “core ISIL” in Iraq and Syria, with air attacks and pending ground assaults on locations the official said were carefully chosen for their strategic value to the Islamic State, also known as ISIL and ISIS. Chief among them is the last remaining 60 miles of Islamic State-controlled territory along the Turkish border in northwest Syria.

The area remains a key entry point for what the official said are about 30,000 foreign fighters from at least 100 countries who have joined the Islamic State. Closure of the area has been long anticipated but delayed, in part due to disagreements with Turkey about how to do it.

Other key target areas in Syria include remaining pockets of militant resistance near Kobane, a border town farther to the east that was retaken by U.S.-backed Syrian Kurdish and Arab forces early this year, and Raqqa, the de facto Islamic State capital in north-central Syria.

“This isn’t just about territory,” the official said. “It is about strategic territory.”

In Iraq, the retaking three weeks ago of the northwest town of Sinjar by Kurdish and Iraqi security forces was seen as a key victory in cutting militant supply lines between Iraq and Syria. This year, Iraqi forces have also driven the Islamic State out of the strategic cities of Baiji and Tikrit.

The Iraqi military, backed by U.S. trainers and advisers, also announced last week that it had seized the last key bridge on the Euphrates River at the city of Ramadi, about 70 miles west of Baghdad, that the militants have occupied for most of the year. “The counterattack is now underway” to retake the city, the official said, warning that doing so may still take many months. Islamic State forces, estimated at about 1,000, have barricaded themselves behind civilians, the official said, and Iraqi counterterrorism forces are proceeding “deliberately . . . it’s going to be street by street.”

The ultimate prize is the militant-occupied city of Mosul, where an offensive by Iraqi forces has been repeatedly delayed.

Overall, the official described the Islamic State as a “degraded force . . . completely different than it was a year ago” when it was expanding throughout both countries. Now, he said, it had been driven out of about a quarter of the territory it once occupied and was severely limited in its movements.

But, the official said, “just because it has been degraded does not mean it is not still extremely dangerous.”

The new “specialized expeditionary targeting force,” which Defense Department officials have said will initially total about 100, is in addition to a continuing campaign of airstrikes and a separate group of about 50 Special Operations troops who are to be sent to Syria to advise opposition forces there.

In October, U.S. and Kurdish commanders also participated in a successful raid on an Islamic State prison in Iraq, which resulted in the first U.S. combat death since Obama pulled out all U.S. ground troops in 2011.