Rival militant organizations on both sides, like Lashkar-e-Tayyeba and the Tehreek e Taliban, of the Afghanistan-Pakistan border have increasingly been teaming up in deadly raids, in what military and intelligence officials say is the insurgents' latest attempt to regain the initiative after months of withering attacks from American and allied forces.
New intelligence assessments from the region assert that insurgent factions now are setting aside their historic rivalries to behave like "a syndicate," joining forces in ways not seen before.
One official said it was "a wake-up call" to find evidence, after the attack on the forward operating base, that the fighters were partisans from three factions with long histories of feuding: the Quetta Shura Taliban of Mullah Muhammad Omar; the network commanded by the Haqqani family; and fighters loyal to the Hekmatyar clan.
These extremist groups have begun granting one another safe passage through their areas of control in Afghanistan and Pakistan, sharing new recruits and coordinating their propaganda responses to American and allied actions on the ground, officials said.
In the past, these insurgent groups have been seen as sharing ideology and inspiration, but less often plans for specific missions.
American and NATO officials said they had seen evidence of loose cooperation among other insurgent groups, including Lashkar-e-Tayyeba and Tehrik-i-Taliban.
Lashkar, a Punjabi group created by Pakistani intelligence to fight in Kashmir, now appear to be teaming up with Pashtun groups like the Afghan and Pakistani Taliban to fight their creators, the Pakistani intelligence and security services.
Pentagon and military officials who routinely engage with their Pakistani counterparts said officials in Islamabad, Pakistan's capital, agreed with the new American and NATO assessments.
The role of senior leaders of Al Qaeda, who are believed to be hiding in the tribal areas of Pakistan, remains important as well, officials said. "They are part of this very complex collusion that occurs between all of these extremist groups," one American official said.