Once close allies, Pakistan and Afghan Taliban are now trading fire. What went wrong?

Pakistan has been the Afghan Taliban’s closest friend for decades. It was Islamabad ⁠that helped give birth to the Taliban in the ⁠early 1990s – as a way to give Pakistan “strategic depth” in its ⁠rivalry with India. What’s gone wrong?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 been heating 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.The escalating conflict is a long way from Islamabad’s historic support for the Taliban. The key questions:Why are the neighbours now 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”.