The United States on Friday expressed support for what it called Pakistan's "right to defend itself" against attacks from Afghanistan's Taliban rulers after Islamabad said earlier in the day that the neighbouring countries were in "open war."

Afghanistan's Taliban rulers had said on Friday they were willing to negotiate after Pakistan bombed their forces in major cities.

"The United States supports Pakistan's right to defend itself against attacks from the Taliban, a Specially Designated Global Terrorist group," a State Department spokesperson said in an emailed statement. US diplomat Allison Hooker said on X she spoke on Friday with Pakistan Foreign Secretary Amna Baloch.

Pakistan is nuclear-armed and its military capabilities are vastly superior to Afghanistan's. However, the Taliban are adept at guerrilla warfare, hardened by decades of fighting with US-led forces, before returning to power in 2021 when Washington withdrew chaotically.

Pakistan is a major non-NATO ally of Washington. The US considers the Afghan Taliban to be a "terrorist" group.

The latest violence erupted after Pakistan's airstrikes on Afghan territory last weekend triggered Afghan retaliatory attacks along the border on Thursday, escalating long‑simmering tensions over Pakistan's claim that Afghanistan shelters Pakistani Taliban militants. Afghanistan denies this and argues Pakistan is deflecting blame for its own security failures.

The State Department spokesperson said Washington was aware of the escalation in tensions and "outbreak of fighting between Pakistan and the Afghan Taliban," adding the US was "saddened by the loss of life."

Both sides reported heavy losses in the fighting, which Pakistan's Defense Minister Khawaja Muhammad Asif said amounted to an "open war".

"The Taliban have consistently failed to uphold their counterterrorism commitments," the State Department said, adding that "terrorist groups use Afghanistan as a launching pad for their heinous attacks."