EU foreign policy chief Baroness Ashton, who led the international team, said Iran had come to the talks with pre-conditions.So long as negotiations are entrusted to a nearly-powerless lead negotiator, Iran obviously feels free to engage in non-productive distractions... after all, their goal is to negotiate for nothing and take a long time doing that.
A different dynamic is required for the forces opposing proliferation to succeed.
I would suggest taking on Amb. John Bolton, empowered with a letter authorizing military and economic coercion, to lead any future round of negotiations... but then the Iranians simply wouldn't show up and then push would come to shove.
...which it likely will, anyway. May as well be moving forward those intervention plans, folks. Bets are we will need to use them.