LAUSANNE, Switzerland (Reuters) - It is one of those concepts that is particularly odious to Russia -- an automatic trigger mechanism under which the U.N. Security Council would be forced to do something.
Now a dispute over that issue threatens to wreck marathon negotiations on a preliminary political framework for a future comprehensive deal that would end the 12-year standoff over Iran's nuclear ambitions. The other major sticking point is Tehran's demands to continue pursuing nuclear centrifuge research and development
