Radio broadcasts by Islamic State militants emerged in December as a new recruitment tool in efforts to lead the Islamist insurgency in eastern Afghanistan. (Reuters)

An Islamic State radio station that had become a symbol of the group’s reach into relatively lawless areas of eastern Afghanistan was leveled Monday evening by a suspected U.S. airstrike, according to officials in Afghanistan’s Nangahar province.

At the time, the station was in the middle of one of its nightly transmissions warning residents to show support for the Islamic State or else be killed.

“It happened as the radio was broadcasting live,” said Hazart Hussain Mashrigiwal, a spokesman for the local police force. “The transmission just stopped operating, and we believe the airstrike was conducted by a drone.”

According to Mashrigiwal, three Islamic State radio technicians were found in the rubble. Ahmad Ali Hazrat, head of the Nangahar provincial council, said at least five Islamic State technicians were killed.

In a statement, the U.S.-led ­coalition in Afghanistan declined to discuss specifics of the reported strike. But Col. Michael Lawhorn, a spokesman for U.S forces in Afghanistan, said the military had conducted “two counterterrorism strikes” in Nangahar’s Achin district late Monday, according to the Associated Press.

“For operational security reasons, we cannot discuss details of the counterterrorism operations,” Lawhorn said.

When the station, dubbed “Caliphate Radio” by its operators, launched in December, it prompted fear throughout Afghanistan as well as Pakistan’s border region, where it also could be heard. Militants were now able to communicate directly with potential recruits and issue public threats to dissenters.

Afghan military leaders initially said they couldn’t determine the origin of the radio broadcasts. That heightened concern among Afghans and Western analysts about Afghan forces’ ability to conduct even basic intelligence operations to halt the Islamic State’s advance.

Now, however, the U.S. military appears to be stepping up its role in efforts to prevent the Islamic State from gaining a foothold in Afghanistan, as the group did in Syria and Iraq — and where it went on to create havens.

Last month, the State Department named the Islamic State’s Khorasan branch — the group’s chapter in Afghanistan and Pakistan — a terrorist organization and imposed sanctions on its leaders. President Obama also gave the Pentagon wider latitude to take offensive action against the militant fighters in Afghanistan, according to media reports.

In an interview published by the New York Times on Sunday, Maj. Gen. Jeffrey Buchanan, deputy chief of staff for U.S. military operations in Afghanistan, said the Pentagon now has the “ability to take the gloves off.”

Still, some Afghan analysts worry that the airstrikes will not deal a lasting blow to the Islamic State in Afghanistan.

The group is made up of former members of the Pakistani Taliban, at least some of whom continue to travel back and forth across the porous Pakistan-Afghanistan border. Taking out a radio station is the easy part, said Bashir Bezhen, a Kabul-based political analyst.

“We need to come up with a strategy to wipe out this threat once and for all,” he said, adding that the Islamic State is still “at a novice stage” in Afghanistan.

Other analysts noted that the dismantling of the radio broadcast may be relatively short-lived, given the Islamic State’s history of improvising. But several listeners from western Pakistan’s tribal belt confirmed that they couldn’t pick up the broadcast Tuesday evening.

Craig reported from Dubai. Mohammad Sharif in Kabul contributed to this report.

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