The Taliban has shuttered or partially shuttered about 50 schools in southeastern Afghanistan this week, a bold display of the insurgency’s power in a part of the country now at the center of the U.S. war effort.

The closings apparently were in response to an Afghan government decision to ban motorcycles in the southern districts of Ghazni province. In the fall, officials in Ghazni outlawed the use of the vehicles after insurgents used unmarked bikes to carry out attacks on civilians and local authorities.

The ban, which is supported by the United States and its allies, has drastically restricted insurgents’ movements, according to Afghan security officials, and increased friction between the Taliban and the government.

Militants responded this week by warning educators and families to keep children at home, Afghan officials said. The message spread quickly through traditional social networks. Of the 36,000 students who usually attend schools in southern Ghazni, about half have yielded to the Taliban threat, officials said.

“In response to the motorcycle ban, they spread the message through elders and mosques saying children should not go to school,” said an official at the Afghan Education Ministry.

By Thursday, dozens of schools across southern Ghazni — for girls as well as boys — were either empty or sparsely attended, according to the ministry.

American officials consider Ghazni a linchpin for stability in central and eastern Afghanistan. For years, the province has been plagued by insurgents, who have regularly attacked U.S. convoys along Highway 1, the main road that connects Kandahar province to Kabul, slicing through Ghazni for 90 miles. As NATO troops continue to leave Afghanistan, Ghazni is the only province that will see a net gain in the number of foreign troops on the ground in the coming months.

Over the past few years, the Taliban has closed or suspended dozens of schools — particularly those attended by girls — in restive parts of the country. But the mass closure of Ghazni’s schools is one of the clearest signs to date of the insurgency’s ability not only to combat NATO and Afghan troops, but also to limit basic social services that Western donors have spent a decade trying to bolster.

Education officials in Kabul worry that they have little leverage to reopen Ghazni’s schools until the provincial government lifts its motorcycle ban. Discarding the policy would be seen by many as a victory for the Taliban — a concession that Afghan and U.S. officials are unlikely to accept.

“We banned the use of such motorcycles because people were being assassinated by those riding them,” said Mohammad Musa Akbarzada, Ghazni’s governor. “But that should have no link with any threat to close down schools.”

Ghazni officials say security in the province has improved since the motorcycle ban took effect. With more than 15,000 students now out of school, however, Afghan officials are struggling to reconcile their push for stability with the Taliban’s response.

“Neither religion nor logic accepts their decision,” Akbarzada said.

Local officials have begun talking with the Taliban about when the schools might be reopened, said Amanullah Iman, a spokesman for the Education Ministry. Afghan officials said they were not optimistic about a quick resolution.

A Taliban spokesman could not be reached for comment.