Ali Bagheri warns that no matter how close talks in Vienna are to revival of 2015 pact, they can still fail until agreement is inked; top Iranian nuclear official to meet with IAEA

Comments by top negotiator come days after European powers warned Tehran is nearing a point where escalation of its nuclear program ‘will have completely hollowed out’ 2015 deal

Nuclear negotiator tweets that the sides will take a few days' break before reconvening to continue discussions

Macron says talks with Iran should have 'broader dynamic' and involve regional powers whose security is directly affected by any accord

Secretary reiterates that US won't allow Tehran to drag out negotiations while advancing with its nuclear program and that Washington will pursue other options if talks fail

Negotiators say 2 proposals submitted by Tehran undo months of work at previous rounds of talks, 'time is running out' for diplomacy; Macron: renewal of talks could be delayed

Top US diplomat says sides will know if Iran is serious by weekend, as Tehran submits proposals on lifting sanctions and curbing enrichment it hopes will form basis of talks

IAEA says Tehran began process of enriching to up to 20% at site dug into mountain, as negotiators fear it's creating facts on the ground

Diplomats say if Tehran does not show seriousness, 'we'll have a problem'; Iran says all previous agreements up for negotiation

Iran's top negotiator and civilian nuclear chief both indicate nothing has been agreed on, previous rounds of nuclear talks can be renegotiated