Developments in Iran Nuclear Standoff:

2013
January:  Iran says it will speed up nuclear fuel work.
February: Iran's supreme leader Ayatollah Ali Khamenei rejects direct nuclear talks with the US.

2012
January:  IAEA confirms Iran is refining uranium to 20% fissile purity.
February:  UN inspectors end talks in Tehran without inspecting disputed military site at Parchin.
April:  Iranian President Mahmoud Ahmadinejad vows Iran will not surrender its nuclear rights.
May:  UN inspectors report they found find traces significantly upgraded uranium at an Iranian site.
July:  EU begins total ban on Iranian oil imports, US expands sanctions.
September:  IAEA demands access to Parchin, Iran calls EU sanctions "irresponsible."
December:  IAEA says it makes progress in talks with Iran.  US imposes more sanctions.