Militants firing from inside Afghanistan killed at least five Pakistani soldiers at a border post in northwestern Kurram district on Sunday, the Pakistan military said, the second such attack since the Islamic Emirate of Afghanistan (IEA) came into power in August.

The Pakistan army said it retaliated, causing heavy casualties, but independent confirmation was not immediately possible because the districts along the mountainous Afghan border are off limits to journalists and human rights organizations, Reuters reported.

“Militants from inside Afghanistan across the international border opened fire on Pakistani troops in Kurram district,” the military’s media wing said in a statement.

The Tehrik-e-Taliban Pakistan (TTP), or Pakistan Taliban, which renewed an allegiance with the IEA after the fall of Kabul, claimed responsibility for Sunday’s attack, Reuters reported.

The Afghan government denied the firing had come from within Afghan territory.

“We assure other countries, especially our neighbors, that no one will be allowed to use Afghan land against them,” Bilal Karimi, deputy IEA spokesman told Reuters.

The IEA late last year played the role of facilitator in talks between the TTP and the Pakistan government.

Those talks fell apart in December and since then there have been a series of attacks on Pakistani forces along the border.

“As per its promises, Taliban (IEA) government should stop such cross-border militants attacks,” Sheikh Rasheed Ahmad, Pakistan’s interior minister, said in a statement.