The Iran nuclear deal was officially implemented on Saturday, as Iran successfully fulfilled its initial key nuclear commitments and the international community relieved major sanctions, including unfreezing about $100 billion of Iranian money. Implementation Day was met with applause from deal supporters in the U.S. and Iran, while critics have raised questions about whether Iran will adhere to its requirements and how it will flex its newfound economic power. Also in recent days, the U.S. and Iran agreed to a prisoner swap that led to the freedom of Washington Post reporter Jason Rezaian and others, and negotiated the release of American sailors detained in Iran. What does the arrival of Implementation Day mean for Iran’s nuclear program and nuclear nonproliferation, and how does it bode for the future of U.S.-Iran relations? We asked Belfer Center experts to weigh in on these and related questions.

The July deal did not solve the Iran nuclear program. At best it delayed it. America and her allies, however, must join together quickly to prepare for the day in a decade or so when the question will again be upon us.

The International Atomic Energy Agency released its “final assessment” yesterday of the possible military dimensions of Iran’s nuclear program.

The “Joint Comprehensive Plan of Action”—the nuclear agreement between the P5+1 and Iran—will enter the implementation phase within months. US policy makers must now consider how best to strengthen the accord as implementation approaches, and in how best engage Iran as implementation proceeds. In this discussion, nonproliferation experts William H. Tobey and Matthew Bunn discuss how to strike an effective balance between cooperation and confrontation in dealing with Iran on the nuclear agreement and beyond. The discussion was moderated by Martin B. Malin and followed by Q&A with the audience.

If Iran can deny inspectors access to military sites, it will create an enormous sanctuary for clandestine nuclear weapons work. The Parchin site alone encompasses hundreds of buildings spread over a dozen square miles. If military sites in Iran are off limits to IAEA inspection, the “strongest nonproliferation agreement ever negotiated” will include the largest loophole in arms control history.

William Tobey, Senior Fellow at the Belfer Center, writes with Judith Miller in Real Clear Politics that it is crucial that the IAEA release the side agreements with Iran regarding the inspections process that will be undertaken to determine the Past Military Dimensions of Iran's nuclear research. They suggest that the debate about the Associated Press draft version of the agreement underscores the need to have the full documents out in public view, and argue that while confidentiality is an important process of the IAEA, that the documents should still be released because they are unlikely to betray nuclear or military secrets of Iran, because Iran is a special case that violated previous agreements, and because Iran struck the agreement with the IAEA and with six other major powers, not just with the IAEA.

It is past time to disclose and explain Iran’s secret deals with the International Atomic Energy Agency. Although the White House has downplayed the importance of these arrangements, calling them “side deals,” they raise questions that go to the heart of President Obama’s claim that the agreement the six leading powers struck with Iran will deny it a bomb for at least 10 to15 years. These “side” understandings are crucial to evaluating the potential effectiveness of the July agreement, although Secretary of State John Kerry claims not to have read them. A draft of one of them has leaked to the Associated Press, but it raises more questions than it answers.

William Tobey, Senior Fellow at the Belfer Center for Science and International Affairs, with Judith Miller, write in Real Clear Politics about steps Congress can take to be confident in the agreement between Iran and the P5+1. They argue that Congress should seek greater clarification on how Iran will comply with its agreements with the IAEA, extend the review period in order to see how Iran responds to some of the early deadlines for compliance under the accord, authorize military force to halt Iran from becoming a nuclear weapons state, establish an independent team of experts to assess Iranian compliance, sell weapons to Israel capable of damaging the fortified Iranian nuclear sites, and increase funding for actions to help counter Iran's regional activities.

"The Iran deal is flawed, but its outright rejection would not advance American interests. Congress should plug some holes and mitigate other weaknesses. Most important, it can provide Iran with stronger incentives to comply with the deal."

On July 28, Hudson Institute hosted a timely conversation on the Iran nuclear deal with Senator Tom Cotton and a panel of leading experts including William Tobey of Harvard University’s Belfer Center for Science and International Affairs and Hudson Senior Fellows Michael Doran, Hillel Fradkin, and Lee Smith.