The Taliban on both sides of the border have a history of raping women and killing children, observers say.
Senior al-Qaeda leaders' apparent ability to function under Iranian protection supports claims that Tehran and bin Laden had a working relationship.
The Taliban have been using advanced weapons available only to the Russian military, according to a security source in western Afghanistan.
The Taliban have denied the allegations.
Mullah Manan Niazi, deputy leader of a splinter Taliban group under Mullah Rasool, said individuals loyal to Mullah Haibatullah Akhundzada sent three suicide bombers to assassinate him.
Among the more than dozen dead, two policemen sacrificed their lives when they stopped the bomber from penetrating the inside of the shrine.
Militants are staunchly opposed to the brotherly relations between Pakistan and Afghanistan, so they leave no stone unturned to undercut their relations, observers say.
ISIS negotiated a deal for safe passage after a humiliating defeat on the Syrian-Lebanese border -- a sign the group is unable or unwilling to continue fighting, a Pakistani think tank says.