Mullah Muhammad Omar states that this decision is based on Mansour Dadullah’s disobedience and carrying out actions which do not comply with the principles of the Islamic Emirate. All members of the Taliban are instructed to completely disassociate themselves from Dadullah, who has not only been removed as commander, but denied any position within the Taliban.
Dadullah hasn't lasted long... only appointed in July of 2007. However his high profile threats to the west not long after his rise in the Taliban are well reported.
Taliban military commander Mansour Dadullah told ABC News that last month he supervised the dispatch of militant cells to United States, Great Britain, Canada and Germany from terror training camps in Pakistan.
"You will, God willing, be witness to more attacks," Dadullah was quoted in the ABC News report of an interview conducted four days ago.
His videos have made it to YouTube. And he claimed that Bin Laden was alive and well in June of 2007, after receiving a letter of condolence from the AQ figurehead on the death of his brother.
Bin Laden "told me to follow in the steps of my brother and urged Muslims to follow the steps of Mullah Dadullah because he was a mujahid", said Dadullah, who was described by Jazeera as a Taliban military leader.
This reaffirms Ray Robison's assertion that the dissent in the ranks of the Taliban, and a possible hostile take over by AQ fighters infiltrating the Afghan Taliban, is indeed true. While Dadullah dutifully appeared to follow Bin Laden's directives, Mullah Omar found him to be too rebellious in his short stint as a Taliban leader to keep.
Per another Long War Journal article on the relationship:
Mujahed, the Taliban spokesman for eastern Afghanistan, did not provide details behind Dadullah's dismissal. Matt Dupee, a contributor to Afgha.com and The Long War Journal, indicated there are "ongoing rifts within the Taliban's upper echelon" over the past year.
"The Taliban’s decision to remove Shah Mansoor as their key commander in the southern areas is a significant development," said Dupee. "Not only does it highlight the ongoing rifts within the Taliban’s upper echelon, but it follows their removal from Helmand’s Musa Qala district and a long list of successful Coalition operations against their command and control capabilities."
Siraj Haqqani has been rising in the ranks of the Taliban in eastern Afghanistan. Combined Joint Task Force-82 has stated Siraj has adopted al Qaeda's ideology and tactics, and is alienating Afghan commanders.