Given the US's dishonest handling of this issue so far. (remember uranium for the medical isotope production. Remember the US's past in terms of overthrowing Iranian governments) Given the Israeli discussions of attacking Iran. (remember exactly who has nuclear arms in the Middle East) I would think that it is up to the US to earn the trust of Iran (and also to keep Israel on a leash) before progress can be made on discussions. Also. Remember that Iran has the right to develop whatever they require to generate electricity using nuclear power.
French investigators confirm wing part is from Flight MH370 (AP)
from the article: Iran FM hopes Geneva nuclear talks 'continue in positive light'