President Barack Obama listens to a question about the Iran nuclear deal during a news conference in the East Room of the White House in Washington, Wednesday, July 15, 2015.

President Barack Obama listens to a question about the Iran nuclear deal during a news conference in the East Room of the White House in Washington, Wednesday, July 15, 2015. Pablo Martinez Monsivais/AP

Obama Offers a Forceful Defense of the Iran Deal

Rejecting the deal 'defies logic,' the president said at a Wednesday news conference.

This is it: President Obama's moment to defend what may become the most lasting and consequential foreign policy decision of his tenure.

"Yesterday was a historic day," the president said during a lengthy press conference Wednesday, where he took many questions. "With this deal, we cut off every single one of Iran's pathways to a nuclear program, a nuclear-weapons program. And Iran's nuclear program will be under severe limits for many years. Without a deal, those pathways remain open. "

Obama announced a day ago that Iran, the U.S. and other nations struck a deal to curb Iran's nuclear program in exchange for relief from sanctions. While some have hailed it as an accomplishment of diplomacy, possibly thwarting a regional arms race and preventing a future U.S. military campaign against Iran, others—most vocally, Republicans and the Israeli government—have called the deal dangerous and say it emboldens a nation that's known to be a state sponsor of terror.

The president acknowledged these concerns, but said the deal serves its purpose. He hinted at lawmakers opposed to the accord, calling their view flawed.

"That because this deal does not solve all those other problems [the U.S. has with Iran]—that that's an argument for rejecting this deal—it defies logic," Obama said. "It makes no sense."

Congress has 60 days to review the 159-page deal, and the White House has a tough sellahead. Senate Majority Leader Mitch McConnell said on Tuesday the administration came into the talks from a "flawed perspective: reaching the best deal acceptable to Iran, rather than actually advancing our national goal of ending Iran's nuclear program." Obama has said that he will veto any legislation to kill the bill. The president needs 34 total senators on his side to ensure that veto won't be overturned, according to NPR.

On Wednesday, Obama asked that lawmakers evaluate "this agreement based on the facts. Not on politics, not on posturing, not on the fact that this is a deal I bring to Congress as opposed to a Republican president, not based on lobbying, but based on what [is in] the national interest in the United States of America."

He said he has spoken to leaders in Congress from both parties and that his national security team is offering "extensive briefings" about it. On Wednesday morning, Vice President Joe Biden went to the Hill to brief House Democrats on the deal.

The accord will reduce Iran's stockpile of enriched uranium, as well as the number of centrifuges and sanctions on the country's economy. It would increase the "breakout" time—the time it would take for Iran to develop a nuclear weapon if it breaks its promise, and calls for international inspections of Iranian facilities.

The final round of negotiations included the extension of a series of self-imposed deadlines as negotiators from Britain, China, France, Germany, Russia, the U.S., and Iran hammered out the details in Vienna. They reached an agreement on the 18th day of talks.

Obama elaborated on what hasn't changed in regards to U.S. relations with Iran.

"We'll still have problems with Iran's sponsorship of terrorism, its funding of proxies like Hezbollah that threaten Israel and threaten the region, the destabilizing activities that they're engaging in, including in places like Yemen. And my hope is that building on this deal, we can continue to have conversations with Iran that incentivize them to behave differently in the region, to be less aggressive, less hostile, more cooperative, to operate the way we expect nations in the international community to behave: But we're not counting on it."

Obama addressed the Israeli government's concerns about the deal. Israeli Prime Minister Benjamin Netanyahu, who has long criticized the negotiations, said Tuesday the agreement had made the world "a much more dangerous place."

"I think there are very good reasons why Israelis are nervous about Iran's position in the world generally," Obama said. "I've said this to Prime Minister Netanyahu, I've said it directly to the Israeli people. But what I've also said is that all those threats are compounded if Iran gets a nuclear weapon."

Diplomacy, Obama said, was the country's best option. "Either the issue of Iran obtaining a nuclear weapon is resolved diplomatically through a negotiation or it's resolved through force, through war," Obama said.

He also acknowledged there are limitations to the United States' negotiating power. "We don't have diplomatic leverage to eliminate every vestige of a peaceful nuclear program in Iran," he said. "But we do have the leverage to make sure they don't have a weapon.

The American public appears somewhat divided on the new agreement. According to anAssociated Press poll conducted in the week before it was announced, 51 percent of respondents said the United States should engage in a diplomatic relationship with Iran. Forty-five percent said the number of sanctions against the country should remain at the current level, and 32 percent said there should be more sanctions.

In Iran, citizens cheered in the streets after the news of the deal broke. To Iranians, the end of sanctions means the end of economic isolation from the broader world.

Obama offered a warning to Iran on Wednesday.

"With this deal, if Iran violates its commitments, there will be real consequences," he said. "Nuclear-related sanctions that have helped to cripple the Iranian economy will snap back into place."

When asked about the Middle East the president would like to see when he leaves office, Obama said he hopes the U.S. mission against the Islamic State there will be succeeding.

"I think my key goal when I turn over the keys to the president, the next president, is that we are on track to defeat ISIL," he said.

But the U.S. cannot solve all the region's problems, Obama said.

"Ultimately, it's not the job of the president of the United States to solve every problem in the Middle East," the president said. "The people in the Middle East are going to have to solve some of these problems themselves, but I think we can provide that next president at least a foundation for continued progress in these various areas."