President Obama on Sunday signed the Iran nuclear deal, officially putting the international agreement into effect.
The president’s signature opens the way for Iran to make major changes to an underground nuclear facility, a heavy water reactor and a site for enriching uranium.
However, the rogue nation will need months to meet those goals and get relief from the crippling economic sanction that will be lifted as part of deal, despite the pact going into effect Sunday.
The seven-nation deal, officially known as the Joint Comprehensive Plan of Action, was reached on July 14, after roughly two years of negotiations.
The so-called “Adoption Day” on Sunday also requires the United States and other participating countries to make the necessary arrangements and preparations for implementation” of the deal, the president said.
"Today marks an important milestone toward preventing Iran from obtaining a nuclear weapon and ensuring its nuclear program is exclusively peaceful going forward," Obama said. "I welcome this important step forward. And we, together with our partners, must now focus on the critical work of fully implementing this comprehensive resolution that addresses our concerns over Iran’s nuclear program."
Senior administration officials said Saturday they understand it's in Iran's best interest to work quickly, but they are only concerned that the work is done correctly.
They insisted that no relief from the penalties will occur until the U.N.'s International Atomic Energy Agency has verified Iran's compliance with the terms of the agreement. They said Iran's work will almost certainly take more than the two months Iran has projected.
The administration officials spoke on a conference call with reporters, but under the condition that they not be identified by name.
As part of the nuclear agreement, Obama on Sunday also issued provisional waivers and a memorandum instructing U.S. agencies to lay the groundwork for relieving sanctions on Iran.
In Iran, Ali Akbar Velayati, a top adviser to supreme leader Ayatollah Ali Khamenei told state TV: "On implementation, all should be watchful that Westerners, particularly Americans, to keep their promises."
Velayati said Iran expects that the United States and other Western countries that negotiated the deal will show their "good will" through lifting sanctions.
Iran's atomic energy chief, Ali Akbar Salehi, told state TV that Tehran was ready to begin taking steps to comply, and awaited an order from President Hassan Rouhani. "We are hopeful to begin in the current or next week," he said.
The IAEA said Sunday that Iran has agreed to allow greater monitoring of its commitment to the deal, going beyond basic oversight provided by the safeguards agreement that IAEA member nations have with the agency. For instance, it allows short-notice inspections of sites the IAEA may suspect of undeclared nuclear activities.
Even as the terms of the deal begin taking effect, recent developments have shown the wide gulf between the U.S. and Iran on other issues.
Fighters from Iran have been working in concert with Russia in Syria, and a Revolutionary Court convicted a Washington Post reporter who has been held more than a year on charges including espionage. The court has not provided details on the verdict or sentence. Further, two other Americans are being detained, and the U.S. has asked for the Iranian government's assistance in finding a former FBI agent who disappeared in 2007 while working for the CIA on an unapproved intelligence mission.
Also, Iran successfully test-fired a guided long-range ballistic surface-to-surface missile.
But the U.S. officials asserted that those actions would be worse if they were backed up by a nation with a nuclear weapon. The officials emphasized that the seven-nation pact is focused solely on resolving the nuclear issue.
The steps being taken by the U.S. come 90 days after the U.N. Security Council endorsed the deal.
The Associated Press contributed to this report.