WASHINGTON (AP) — President Donald Trump withdrew the U.S. from the landmark nuclear accord with Iran, abruptly restoring harsh sanctions in the most consequential foreign policy action of his presidency. He declared he was making the world safer, but he also deepened his isolation on the world stage and revived doubts about American credibility.

The 2015 agreement, which was negotiated by the Obama administration and included Germany, France and Britain, had lifted most U.S. and international economic sanctions against Iran. In exchange, Iran agreed to restrictions on its nuclear program, making it impossible to produce a bomb and establishing rigorous inspections.

But Trump, a severe critic of the deal dating back to his presidential campaign, said Tuesday in a televised address from the White House that it was "defective at its core."

U.S. allies in Europe had tried to keep him in and lamented his move to abandon it. Iran's leader ominously warned his country might "start enriching uranium more than before."

The sanctions seek to punish Iran for its nuclear program by limiting its ability to sell oil or do business overseas, affecting a wide range of Iranian economic sectors and individuals.

Major companies in the U.S. and Europe could be hurt, too. Treasury Secretary Steven Mnuchin said that licenses held by Boeing and its European competitor Airbus to sell billions of dollars in commercial jetliners to Iran will be revoked. Certain exemptions are to be negotiated, but Mnuchin refused to discuss what products might qualify.

He said the sanctions will sharply curtail sales of oil by Iran, which is currently the world's fifth largest oil producer. Mnuchin said he didn't expect oil prices to rise sharply, forecasting that other producers will step up production.

Iran's government must now decide whether to follow the U.S. and withdraw or try to salvage what's left with the Europeans. Iranian President Hassan Rouhani said he was sending his foreign minister to the remaining countries but warned there was only a short time to negotiate with them.

Laying out his case, Trump contended, "If we do nothing, we know exactly what will happen. In just a short period of time, the world's leading state sponsor of terror will be on the cusp of acquiring the world's most dangerous weapons."

The administration said it would re-impose sanctions on Iran immediately but allow grace periods for businesses to wind down activity. Companies and banks doing business with Iran will have to scramble to extricate themselves or run afoul of the U.S. government.

Meanwhile, for nations contemplating striking their own sensitive deals with Trump, such as North Korea, the withdrawal will increase suspicions that they cannot expect lasting U.S. fidelity to international agreements it signs.

Former President Barack Obama, whose administration negotiated the deal, called Trump's action "misguided" and said, "The consistent flouting of agreements that our country is a party to risks eroding America's credibility and puts us at odds with the world's major powers."

Yet nations like Israel and Saudi Arabia that loathed the deal saw the action as a sign the United States is returning to a more skeptical, less trusting approach to dealing with adversaries.

Israeli Prime Minister Benjamin Netanyahu welcomed Trump's announcement as a "historic move."

Trump, who repeatedly criticized the accord during his presidential campaign, said Tuesday that documents recently released by Netanyahu showed Iran had attempted to develop a nuclear bomb in the previous decade, especially before 2003. Although Trump gave no explicit evidence that Iran violated the deal, he said Iran had clearly lied in the past and could not be trusted.

Iran has denied ever pursuing nuclear arms.

There was a predictably mixed reaction from Congress. Senate Majority Leader Mitch McConnell, a Kentucky Republican, said the Iran deal "was flawed from the beginning," and he looked forward to working with Trump on next steps. House Minority Leader Nancy Pelosi, a California Democrat, slammed Trump in a statement, saying this "rash decision isolates America, not Iran."

In a burst of last-minute diplomacy, punctuated by a visit by Britain's top diplomat, the deal's European members had given ground on many of Trump's demands for reworking the accord, according to officials, diplomats and others briefed on the negotiations. Yet the Europeans realized he was unpersuaded.

Trump spoke with French President Emmanuel Macron and Chinese leader Xi Jinping about his decision Tuesday. Hours before the announcement, European countries met in Brussels with Iran's deputy foreign minister for political affairs, Abbas Araghchi.

In Iran, many are deeply concerned about how Trump's decision could affect the already struggling economy. In Tehran, Rouhani sought to calm nerves, smiling as he appeared at a petroleum expo. He didn't name Trump directly, but emphasized that Iran continued to seek "engagement with the world."

The first 15 months of Trump's presidency have been filled with many "last chances" for the Iran deal in which he's punted the decision for another few months, and then another. As he left his announcement Tuesday, he predicted that Iranians would someday "want to make a new and lasting deal" and that "when they do, I am ready, willing and able."

Even Trump's secretary of state and the U.N. agency that monitors nuclear compliance agree that Iran, so far, has lived up to its side of the deal. But the deal's critics, such as Israel, the Gulf Arab states and many Republicans, say it's a giveaway to Tehran that ultimately would pave the way to a nuclear-armed Iran.

For the Europeans, Trump's withdrawal constitutes dispiriting proof that trying to appease him is futile.

Although the U.S. and Europeans made progress on ballistic missiles and inspections, there were disagreements over extending the life of the deal and how to trigger additional penalties if Iran were found in violation, U.S. officials and European diplomats have said.

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Associated Press writers Matthew Lee, Jill Colvin, Zeke Miller and Ken Thomas in Washington and Amir Vahdat and Nasser Karimi in Tehran, Iran, contributed to this report.