Afghanistan said its forces opened fire on Pakistani jets over Kabul on Sunday after explosions and gunfire shook the capital, adding to regional instability already heightened by U.S.–Israeli strikes on Iran and retaliatory attacks on American targets in Gulf states.

The Taliban-led government has faced Pakistani airstrikes against what Islamabad says are militant-linked facilities in recent days — accusations Kabul denies, insisting it does not harbor armed groups targeting Pakistan.

The surge in hostilities marks some of the heaviest fighting in years between the two neighbors and has fueled fears of a prolonged conflict along their 1,615-mile border. Several countries, including Qatar and Saudi Arabia, have urged restraint and offered to mediate a ceasefire.

Explosions were heard across parts of Kabul before dawn, followed by bursts of gunfire, according to a Reuters witness. It was not immediately clear what had been targeted or whether there were any casualties.

Taliban spokesperson Zabihullah Mujahid said Afghan air defenses were responding to Pakistani aircraft over the capital.

“Air defense operations were carried out in Kabul against Pakistani aircraft. Kabul residents should not be concerned,” Mujahid said.