Pakistan carried out air strikes on Afghanistan’s major cities overnight, officials in Islamabad and Kabul said on Friday, escalating months of border clashes between the Islamic neighbours.

The air and ground strikes, which hit Taliban military posts, headquarters and ammunition depots in multiple sectors along the border, came after Afghanistan launched an attack on Pakistani border forces, the officials said.

Both sides reported heavy losses in the fighting, which Pakistan’s defence minister said amounted to an “open war”.

Tensions have heated up since Pakistan launched air strikes on militant targets in Afghanistan last weekend.

Earlier, border clashes between the two countries killed dozens of soldiers in October until negotiations facilitated by Turkey, Qatar and Saudi Arabia ceased the hostilities and a fragile ceasefire was put in place.

Why are the neighbours at odds?

Pakistan welcomed the return to power of the Taliban in 2021, with then-Prime Minister Imran Khan saying that Afghans had “broken the shackles of slavery”.

But Islamabad soon found that the Taliban were not as cooperative as it had hoped.

Islamabad says that the leadership of militant group Tehreek-e-Taliban Pakistan (TTP) and many of its fighters are based in Afghanistan, and that armed insurgents seeking independence for the southwestern Pakistani province of Balochistan also use Afghanistan as a safe haven.

Militancy has increased every year since 2022 with attacks by the TTP and Baloch insurgents growing, according to Armed Conflict Location & Event Data, a global monitoring organization.

Kabul for its part has repeatedly denied allowing militants to use Afghan territory to launch attacks in Pakistan.

The Afghan Taliban say Pakistan harbours fighters from its enemy, Islamic State, a charge Islamabad denies.

Islamabad says the ceasefire did not hold long due to continued militant attacks in Pakistan from Afghanistan, and there have been repeated clashes and border closures since then that have disrupted trade and movement along the rugged frontier.

What sparked the latest clashes?

The day before last weekend’s strikes, Pakistani security sources said they had “irrefutable evidence” that militants in Afghanistan were behind a recent wave of attacks and suicide bombings which targeted Pakistani military and police.

The sources listed seven planned or successful attacks by militants since late 2024 that they said were connected to Afghanistan.

One attack last week that killed 11 security personnel and two civilians in Bajaur district was undertaken by an Afghan national, according to Pakistani security sources. This attack was claimed by the TTP.

WHO ARE THE PAKISTANI TALIBAN?

The TTP was formed in 2007 by several militant outfits active in northwest Pakistan. It is commonly known as the Pakistani Taliban.

The TTP has attacked markets, mosques, airports, military bases, police stations and also gained territory - mostly along the border with Afghanistan, but also deep inside Pakistan, including the Swat Valley. The group was behind the 2012 attack on then schoolgirl Malala Yousafzai, who received the Nobel Peace Prize two years later.

The TTP also fought alongside the Afghan Taliban against U.S.-led forces in Afghanistan and hosted Afghan fighters in Pakistan. Pakistan has launched military operations against the TTP on its own soil with limited success, although an offensive that ended in 2016 drastically reduced attacks till a few years ago.

What happens next?

Pakistan is likely to intensify its military campaign, analysts say, while Kabul’s retaliation could come in the way of raids on border posts and more cross-border guerrilla attacks to target security forces.

On paper, there is a wide mismatch between the military capabilities of two sides. At 172,000, the Taliban have less than a third of Pakistan’s personnel.

The Taliban do possess at least six aircraft and 23 helicopters but their condition is unknown and they have no fighter jets or effective air force.

Pakistan’s armed forces include more than 600,000 active personnel, have more than 6,000 armoured fighting vehicles and more than 400 combat aircraft, according to 2025 data from the International Institute for Strategic Studies. The country is also nuclear armed.