As the US and Iran inch toward the table, a sticky wicket could be the US relationship with the Mujahedin e-Khalq, a paramilitary group that militantly opposes the Tehran government. The US, meanwhile, shelters the MEK in a base on the Iraq-Iran border that has become the organization's operations center.
The US agrees in classing the MEK as a terrorist organization, and has disarmed the fighters in the Iraq base. But the military covertly uses the organization as an intelligence tool and a counterweight to Iran. As the US demands that Iran cease support for the militias terrorizing Baghdad, Iran may ask for a reciprocal cutoff of the MEK.