Most talks have involved the permanent five members of the UN Security Council, plus Germany (the "P5+1"). These countries either side with the US position on Iranian intransigence (UK, France, Germany), or share Iran’s view of its own sovereignty and even benefit from the standoff (Russia, China). There are no participants in the talks that bridge the gap.
In 2010, Turkey and Brazil joined forces to broker a pact in which Tehran agreed to limitations on its nuclear program that President Obama had previously endorsed. (Washington nonetheless rejected the deal for being too little, too late). Similarly, while hosting America’s Central Command military base, Qatar explores gas fields with Tehran and hopes to include Iran (and Israel) in a new Gulf security arrangement. And India has economic, political, and strategic interests with both Tehran and Washington, making it an important interlocutor.
Not only can these and other countries provide a safe political space for both sides, but they can also tangibly help solve the nuclear problem and its related issues. They can, for instance, host an international reprocessing center to store spent nuclear fuel; they can invest in Iran’s energy sector to bolster trade, among other incentives and restrictions.
If there is to be any progress in the region, diplomacy ought to be given the attention and resources it deserves.