"Tehran must understand that it cannot escape or evade the choice before it: meet your international obligations or face the consequences," said President Obama.

Iran says its nuclear program is for peaceful purposes and it is not giving up any of its right in moving to return to talks with permanent members of the U.N. Security Council and Germany - a group known as the P5+1. 

President Obama says it is an opportunity that Tehran needs to seize seriously.

"I think they should understand that because the international community has applied so many sanctions, because we have employed so many of the options that are available to us to persuade Iran to take a different course, that the window for solving this issue diplomatically is shrinking," said Obama.

Sanctions against Iranian oil exports and its banking sector have hurt Iran's economy. 

And foreign policy analyst Malou Innocent says that has helped bring Iran back to nuclear talks.

“The Iranian rial since December has plummeted in value," said Malou Innocent. "We have seen an increase in unemployment, an increase in inflation. So really the Obama administration wants to continue that pressure, and they believe that that is what has brought Iran to the negotiating table.”

Setbacks for Iranian President Mahmoud Ahmadinejad in parliamentary elections have opened internal political divisions about Iran's nuclear ambitions.

“So there has been an increase in the rhetoric on Khamenei's part, on the Ayatollah's part, to engage with the P5+1 and also to begin opening up the Iranian nuclear program," she said.

Concerns about Tehran's nuclear ambitions come as Iran stands by Syrian President Bashar al-Assad and continues to arm Hezbollah.

Johns Hopkins University professor Ruth Wedgwood says Iran's return to talks does not diminish its drive for influence.

“Iran wants to be the dominant player in the region," said Ruth Wedgwood. "And clearly they are calling the shots in Iraq.”

The Obama administration is denying Russian media reports that Washington is asking Moscow to warn Iran that these talks are its “last chance” to resolve the nuclear standoff peacefully. U.S. officials say they want substantive results, not talks that can be used to cover additional nuclear activity.