There is a paradox in Afghanistan, when it comes to Afghanistan’s two strongest neighbors i.e. Iran and Pakistan. I do not mention China, because the Afghan-Chinese borders are very tiny and very unfriendly geographically speaking. Moreover China is not happy to get involved in Muslim battlefields, because the opposite sides attack China’s Muslim province of Xin Jiang.
Map Pashtunistan
The paradox is that for Iran’s security peace in Afghanistan is essential, in order to have stability at the Iranian-Afghan borders. While for Pakistan national security war in Afghanistan is good, because a stable and strong Afghan government would immediately raise the issue of Pashtunistan. For Pashtunistan See “The 2 Faces of the Taliban”.
https://iakal.wordpress.com/2016/07/12/the-2-faces-of-the-taliban/
On the other hand, war in Afghanistan is good for Iran’s energy policy, because it prevents the oil and gas of Central Asia from reaching Pakistan and India. Iran wants the oil and gas of Central Asia to go to Europe and South Asia through Iran. On the contrary Pakistan’s energy policy requires peace in Afghanistan, in order for the oil and gas of Central Asia to flow to Pakistan, and through Pakistan.
Map Central Asia
The paradox is that Iran’s energy policy needs war in Afghanistan, while Iran’s national security needs peace, while Pakistan’s energy policy needs peace in Afghanistan, but Pakistan’s national security needs war.