Three reasons stand out.
First, Lt-Gen Taj was widely known to be close to former General-President Pervez Musharraf and was also a distant relative, just like former Military Intelligence chief Maj-Gen Nadeem Ijaz.
When the new government took oath, leaders of the Pakistan Muslim League-Nawaz alleged that President Musharraf was continuing to hatch conspiracies against their party by trying to break the coalition and solemnise an unholy marriage between the Pakistan People's Party and the erstwhile King's Party, the Pakistan Muslim League-Quaid.
The allegation did stick because from the president's standpoint, it made sense to bring the PPP and the PMLQ together along with other smaller parties to isolate the PMLN and prevent it from forming a government in the Punjab.
The dirty-tricks brigade, according to the PMLN, comprised the MI and the ISI. While General Ashfaq Pervez Kayani, who took over from Musharraf, posted out the MI chief, DG-ISI Lt-Gen Taj remained in the driver's seat.
Not only was the PMLN unhappy, even the PPP began making noises about cleansing the ISI.
Second, on July 7 the Indian embassy in Kabul was bombed. Fingers were pointed at ISI by Kabul and New Delhi. Shortly thereafter, the New York Times reported that CIA deputy director, Stephen R Kappes, had arrived in Pakistan July 12 on a secret visit with Adm Mike Mullen, chairman of the US Joint Chiefs of Staff, and confronted Islamabad allegedly with new evidence on ISI's involvement in the attack. Pakistan denied accusations emanating from Washington, Kabul and New Delhi.
On July 27, Prime Minister Yousaf Raza Gilani left for his first official visit to the United States. Even as he was winging to Washington, the Press Information Department issued an official notification calling for placing the ISI for all purposes, operational, financial and administrative, under the interior ministry.
It was a sloppy attempt passed off as a step towards restructuring the ISI. Asif Ali Zardari, in Dubai at the time, even gave an interview to a Pakistani newspaper, calling the notification an historic step and noted that "Nobody will say that this agency is not under the control of an elected government as the interior ministry will be responsible for responding to allegations against the ISI."
Clearly, he was responding to internal and external allegations against the ISI and the government's lack of control over the agency. Within 24 hours, however, the PID issued another clarification putting the earlier order in abeyance and promising a fresh notification which hasn't come yet.
Meanwhile, in Washington, the PM reportedly had to face questioning on the role of the ISI again and the issue of who controls it and to what extent. The internal unrest and external allegations were beginning to double-envelop the agency.
Much is being made of Kayani's attempt to surround himself with his own men. That is only partially true and in many ways legitimate too. However, it does not seem that he would have unnecessarily pushed Lt-Gen Taj out of the ISI in less than a year of the latter's having taken charge of the agency if internal and external actors had not begun to cast doubts over the agency's internal and external conduct.
This is where the third reason comes in. If Lt-Gen Taj has to go, who should take over?
The new chief, Lt-Gen Pasha, has been planning and coordinating the army's effort in the tribal areas. He is known as a straight shooter and a professional soldier. He was trusted by Musharraf and continued working as DG-MO under Kayani. He may be no Napoleon, but he has had to perform a very difficult task, one in which success cannot be quantified in Clausewitzean terms.
The reasons for Taj's transfer and Pasha's credentials worked to the latter's advantage. Consider.
If Lt-Gen Taj had to be relieved, let him be given a corps since he was promoted from Maj-Gen and placed in charge of the ISI. He now gets to have the experience of commanding a corps and be part of the corps commanders' collegium without being directly involved in counterinsurgency operations and/or gathering intelligence.
The move also takes care of bickering by domestic political actors. As for external complaints, how about putting in charge of the ISI an officer who has closely coordinated counterinsurgency operations; that clearly signals to all concerned that the army and the ISI are on the same page as far as the war on terror is concerned.
As for Kayani, the decision allows him to have a trusted lieutenant at a very important post, someone who is in lock step with him. But what is most significant is the fact that the changes came after Kayani's return from China and his meeting with Gilani. The message: the army and the civilian government are in sync.
A further evidence of this is the move to relieve and supersede DG-Counter Intelligence Maj-Gen Nusrat Naeem and bring in his place Maj-Gen Zahir ul Islam, former GOC 12 Division. Naeem as DG-CI was in charge of a wide range of activities, including the so-called political wing of the agency. In fact, while the seven Major-Generals promoted to the next rank include two from the ISI, two others, Nusrat Naeem and Asif Akhtar (both ISI) have not made it to the next rank.
Similarly, Maj-Gen Mohammad Siddique who was serving in the GHQ but was former acting chairman of the National Accountability Bureau has also been superseded. While at NAB, Siddique was responsible for pursuing cases against, among others, Zardari, now president.
The appointments, postings, promotions and supersessions are therefore a mixed bag. Some have been made on professional bases. Others have political and strategic tones to them. All have been made to sync with the usual round of such activity.
Kayani, like Musharraf before him, knows it's important to clear the decks before going into battle.
The writer is Op-Ed Editor Daily Times and Consulting Editor The Friday Times. He also hosts a political talk-show for Dawn News. The views expressed are his own.