Afghanistan attacked Pakistani military positions along the border late on Thursday in retaliation for Pakistani airstrikes, the Taliban said, adding to fears of a renewed escalation of violence between the neighbors.
Videos shared by Afghan security forces showed Humvees driving through dark, mountainous terrain at night, lit by flashes of gunfire. Sustained bursts of automatic fire could be heard in the background.
Reuters could not independently verify the location, timing, or authenticity of the images.
Pakistan was responding to "unprovoked fire" by Afghan forces along the border, the Information Ministry in Islamabad said.
Afghan forces opened fire on posts in Pakistan's mountainous northwest, sparking more than two hours of fighting before Pakistani troops retaliated, Pakistani officials said, speaking on condition of anonymity as they were not authorized to speak to the media.
Clashes threaten fragile ceasefire
The clashes along the 2,600-km (1,615-mile) are the latest flare-up to threaten a fragile ceasefire following deadly clashes in October.
Earlier this week, the Taliban warned it would make an "appropriate and measured response" to airstrikes launched by Pakistan over the weekend on what Islamabad said were camps of militants from Tehreek-e-Taliban Pakistan (TTP) and Islamic State in Khorasan Province in eastern Afghanistan.
Islamabad says TTP leaders operate from Afghan territory and use it as a safe haven to plan attacks inside Pakistan, a charge Kabul denies.
"In response to repeated provocations and violations by Pakistani military circles, large-scale offensive operations have been launched against Pakistani military positions and installations along the Durand Line," the spokesperson for Afghanistan's Taliban administration, Zabihullah Mujahid, said in a post on X.
"Specialized laser units have also begun operations along the Durand Line, which would take advantage of the darkness of night," Mujahid said in a separate statement.
Pakistan said it was boosting security nationwide this week, placing forces on "high alert" and accelerating intelligence-based operations, arresting dozens of suspected militants, their handlers and facilitators, including Afghan nationals.