WASHINGTON >> For years, the Joint Special Operations Command, known throughout the Pentagon as JSOC, has provided standing forces of U.S. commandos to track down terrorist leaders overseas. Now, in announcing that it is deploying a small team of special operators to Iraq to carry out raids against high-value Islamic State leaders in Iraq and Syria, the Pentagon is turning to its elite team of manhunters once again.

The defense secretary, Ash Carter, did not use the acronym JSOC when he disclosed his plans before a House hearing on Tuesday; instead, he referred to a “specialized expeditionary targeting force.” But the commandos — Defense Department officials said they will number at least 100, including support personnel — will have a mission similar to (but smaller than) the one they carried out in tandem with President George W. Bush’s surge of U.S. troops in Iraq in 2007.

There, commandos conducted a series of high-tempo, nightly raids to capture or kill fighters from al-Qaida and other former Baathist groups in Iraq.

Now, the new enemy is the Islamic State, which includes members of the old enemy who were not killed last time. Many officials said privately that they viewed the new deployment as only the beginning of what could be a phased intensification of the war effort in Iraq and Syria.

The newly deployed commandos “will conduct raids,” said Col. Steven H. Warren, spokesman for the U.S.-led coalition against the Islamic State in Baghdad.

“Absolutely no question about that,” Warren said. “Their presence will focus on high-value individuals, high-value targets.”

He said that the Defense Department preference would be to capture rather than kill Islamic State leaders, “because that allows us to collect intelligence and gain additional insight” into the group’s activities and structure. But he added that “we see this as conducting operations to defeat ISIL,” using another name for the Islamic State. “That’s our mission: Defeat ISIL.”

The White House and Pentagon are under increasing pressure to show that the United States is taking more concrete steps to combat the Islamic State. In a reflection of that pressure, Carter surprised several of his top aides by inserting the plan for the additional commandos into his prepared testimony the night before Tuesday’s hearing, even though it had not been fully developed.

“It was his bright, shiny toy,” said one senior Pentagon official, noting it was the kind of initiative President Barack Obama has demanded from his national security team.

Now military planners at the JSOC headquarters at Fort Bragg, N.C., and in Washington are scrambling to catch up with their boss’ unexpected announcement, and fill in details of the bare-bones proposal, such as what happens to any detainees U.S. commandos seize in the raids.

For Obama, who has been loath to send more troops to the region after more than a decade of war, the insertion of the commandos represents an effort to intensify the war effort without committing a large U.S. fighting force like, say, a division of ground combat troops. Defense officials said the new special operators would work with Kurdish and Iraqi troops in Iraq, and possibly Syrian and Arab troops during targeted raids in Syria.

So the administration is taking smaller steps to increase pressure on the Islamic State without fundamentally appearing to alter its cautious strategy.

“The president is trying to find the balance between being all in, with a large deployment of ground forces, and being not in,” said Aaron David Miller, a vice president with the Woodrow Wilson International Center for Scholars.

Obama has so far sent 3,500 U.S. forces to Iraq since the Islamic State took a huge amount of land and declared a caliphate.

Warren and other Defense Department officials declined to detail how the commandos would operate, saying that they do not want to compromise U.S. capabilities. But they held up the example of a commando raid in May that resulted in the killing of a midlevel Islamic State leader and the capture of his wife as an example of what is to come.

On May 16, around two dozen Delta Force commandos entered Syria aboard Black Hawk helicopters and V-22 Ospreys from Iraq and killed Abu Sayyaf, who U.S. officials described as the Islamic State’s “emir of oil and gas.”

Sayyaf’s wife, Umm Sayyaf, was captured and taken to Iraq, U.S. officials said, where she was questioned and detained at a military facility. They said the U.S. forces were able to seize laptop computers, cellphones and other materials from the site.

But the case has raised the question of what will be done with Islamic State leaders who are captured alive. Had Sayyaf been detained, officials said at the time, the plan was to interrogate him in Iraq and then send him to the United States for criminal prosecution.

The White House press secretary, Josh Earnest, said Wednesday that Islamic State leaders captured by the commandos would not be sent to the military prison at Guantanamo Bay, Cuba, which the president is trying to close. He said the fates of prisoners would be decided case by case.

The new deployment of commandos to Iraq “feels like precisely that JSOC type of strategy” that the Bush administration employed during the Iraq surge, said Ilan Goldenberg, director of the Middle East Security Program at the Center for a New American Security.

“The difference is, when we had the surge, we had a much clearer strategy for how we were going to defeat al-Qaida in Anbar,” Goldenberg said, referring to the Sunni Awakening, in which Sunni tribesmen agreed to work with U.S. troops in their villages and towns.

But today many of those Sunni tribesmen believe that they were betrayed and squeezed out of power by the Shiite-led government of Prime Minister Nouri al-Maliki. Whether they will be willing to sign on to the same strategy again, Goldenberg said, is a big question.

Some Defense Department officials expressed concern about the ad hoc nature of the commando plan and its announcement, noting that the 50 Special Operations forces that Obama ordered to eastern Syria a month ago to train and advise Syria opposition fighters still have not arrived.

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