U.S. responds saying Iran is disappointed by international caution about doing business with Tehran.
The letter, delivered Friday, is aimed at proposals by Republicans to add new sanctions to the Iran Sanctions Act.
U.S. officials say there have been more than 30 close encounters with Iranian vessels in the Gulf so far this year - more than double the amount from the same period last year.
Iran's central bank approves the opening of branches overseas, German paper reports.
After political storm and White House denial, Clinton calls for reauthorization of sanctions on Iran, vows to fight Iran’s support for terrorism.
AIPAC says it is 'deeply troubled' by alleged secret exemptions while RJC says 'President Obama and his fellow Democrats have never been straightforward with the American people about Iran.'
Iran was allowed to exceed the agreement's limits on how much low-enriched uranium it could keep in its nuclear facilities in order to meet deadline, Washington-based think tank says.
The Obama administration last week slapped sanctions on the three, saying they are based in Iran, which it accused of helping transfer money and fighters from South Asia to the Mideast.
UN chief Ban Ki-moon's first report on Iran 'goes beyond the appropriate scope,' U.S. Ambassador to UN says.
Sens. Ben Cardin of Maryland and Charles Schumer of New York among senators who introduced legislation aimed at renewing Iran Sanctions Act of 1996, due to expire at year's end.