The United States reached a preliminary nuclear agreement with Iran on Sunday, signaling progress between the two nations for the first time in 34 years. The preliminary agreement states that the U.S. will ease harsh economic sanctions in return for Iran's compliance in limiting its nuclear ambitions. 

On Saturday, President Obama said that reaching a final agreement "won't be easy, and huge challenges remain ahead."

However, the deal marks a huge step forward in communications between the U.S. and Iran, and opens an array of opportunities that have not been possible since Jimmy Carter was president, The New York Times confirms. 

"No matter what you think of it, this is a historic deal," said Vali R. Nasr, the dean of the Johns Hopkins School of Advanced International Studies. "It is a major seismic shift in the region. It rearranges the entire chess board."

In 2007, Obama affirmed that he wanted to open relations with Iran. He said he would pursue "aggressive personal diplomacy" with Iranian leaders. 

The accord was reached in the middle of the night during talks in Geneva  between Iran, the United States, Russia, China, France, Britain and Germany, according to Reuters. It also gained the endorsement of Iranian clerical Supreme Leader Ayatollah Ali Khameini. 

The current deal allows a six-month period of limits to Iran's nuclear program in exchange for up to $7 billion in sanctions relief. Yet, both the program and some sanctions will remain in place. 

The accord states that Iran will halt all testing at a heavy-water reactor, and any reference to Iran's enrichment of uranium will be tied to a final agreement.  

"Now the really hard part begins and that is the effort to get the comprehensive agreement, which will require enormous steps in terms of verification, transparency and accountability," said Secretary of State John Kerry. 

The deal could also alter America's relationship with other countries in the Middle East, including war-torn Syria and Afghanistan, where the Iranians could help broker a deal with the Taliban. 

On Sunday, American allies in the region such as Saudi Arabia and Israel denounced the agreement. Israeli Prime Minister Benjamin Netanyahu called the deal a "historic mistake."

Some lawmakers, including Democrats, believe the deal eases sanctions without gaining enough concessions from Iran. 

"It was strong sanctions, not the goodness of the hearts of the Iranian leaders, that brought Iran to the table," said Senator Charles E. Schumer, Democrat of New York.

The deal may also hinder the possibility of a peace accord between Israel and the Palestinians. 

"The Palestinian issue is the big casualty of this deal," said Bruce O. Riedel, a former administration official who is now a senior fellow at the Brookings Institution. "Now that they have an Iran deal, over the strong objections of Israel, it's going to be very hard to persuade Netanyahu to do something on the Palestinian front." 

Obama called Secretary Kerry Sunday afternoon to go over the wording of the accord, particularly the preamble. The preamble refers to a "mutually defined enrichment program" with Iran, which allows Iran to enrich uranium, which is a privilege that is denied to Iran by the United Nations.