One of the main theories being investigated by western forces in Afghanistan is that Tuesday's bombing aimed at Shia targets, which killed 58 people, was carried out by the Haqqani network.
If this is true, it would point the finger at Pakistan's Inter Services Intelligence agency, which has nurtured a long relationship with this Afghan group, and has been publicly accused by the US of using it to orchestrate terrorist attacks in Kabul.
In September, Admiral Mike Mullen, the outgoing Chairman of the Joint Chiefs of Staff, told a Senate committee that the US had "credible intelligence" that the Haqqani network had carried out spectacular strikes in Kabul, including against the American Embassy, and that it acted as a "veritable arm" of the ISI. Pakistan slammed the comments as "irresponsible" and denied the accusation, in effect, of state backed terrorism.
However there have been a number of indicators that suggest the latest attacks may also have sprung from the Haqqani network. The staging of a coordinated multiple bombing operation (with targets in Kabul, Mazar-i-Sharif and Kandahar) is beyond the capabilities of almost all Taliban groups.
The mainstream Taliban, or Quetta Shura, have denied responsibility for Tuesday's bombings. In previous assaults on the Intercontinental Hotel and US Embassy, the Haqqani network has shown the capability to mount ambitious, coordinated, strikes.
The relationship between this group and the ISI goes back to the Soviet war, when the Pakistanis channelled weapons to its patriarch, Jalaludin Haqqani, who commanded forces in the border area around Tora Bora.
So what could the ISI's possible motive be for endorsing such a move, particularly when Pakistan's own Shia/Sunni tensions have historically been a good deal more aggravated than those in Afghanistan?
