WASHINGTON — President Donald Trump announced Tuesday that he will pull out of the Iran nuclear deal, the most consequential foreign policy decision of his presidency so far, and reinstate a sweeping array of U.S. economic sanctions on Tehran that were lifted under the landmark 2015 accord.

Although it was widely expected, Trump's decision sent shock waves around the globe and could isolate the United States among its European allies, which all had pleaded with Trump to keep the historic pact intact while they tried to fix its flaws.

Although Trump called the Iran deal "decaying and rotten" and "defective at its core," he did not offer any specifics of how he would replace it or what he would do to restrain Iran from rebuilding its nuclear infrastructure should it choose to do so.

Speaking from the Diplomatic Reception Room at the White House, Trump said he would impose the "highest level of economic sanctions" on Iran and warned other countries of violating U.S. law. The White House said the new sanctions would target Iran's energy, petrochemical and financial sectors, although it provided no specifics.

"If I allowed this deal to stand there would be a nuclear arms race in the Middle East," Trump said, adding that it sends a "critical message" to friends and adversaries: "The United States no longer makes empty threats."

Trump faced a May 12 deadline to renew waivers that eased sanctions on Iran's central bank, which deals with Iran's oil exports. Another set of sanctions, focused on more than 400 Iranian companies, individuals and sectors, is up for renewal July 11.

Trump could reimpose only the central bank sanctions. That would give companies or countries 180 days to reduce their oil purchases from Iran, giving them more time to search for a solution. Hitting all 400 targets at the start would be far more drastic and could create a confrontation with Iran.

Reimposing of any sanctions effectively takes the United States out of the agreement.

The decision pleased Iran hawks in Congress and U.S. allies in Israel and Saudi Arabia, which both agreed with Trump that the deal gave Iran too much leeway to someday rebuild nuclear programs that could be used to produce a bomb.

Trump's new national security team, Secretary of State Mike Pompeo and national security adviser John Bolton, were vociferous critics of the deal. Trump said Pompeo is en route to North Korea for the second time in a month to help prepare for a planned summit with North Korean ruler Kim Jong Un.

The other signatories to the Iran accord _ Britain, France, Russia, China and Germany _ have indicated they will continue to honor the agreement. But countries or companies that continue to invest in or do business with Iran could run the risk of violating U.S. sanctions, with vast political and economic repercussions.

Reinstating sanctions on Iran's oil exports would most directly affect Europe, Japan and South Korea. But it probably would lead to a jump in oil prices and higher U.S. prices at the pump this summer. Beneficiaries of rising crude oil prices would include Russia, Venezuela and other producers.

Iran has given mixed signals as to whether it also would withdraw from the deal and try to resume nuclear activities that were blocked by the accord. The International Atomic Energy Agency, the United Nations nuclear watchdog agency, has repeatedly found that Iran is complying with the deal's requirements.

The diplomatic pact, which has successfully blocked Tehran's ability to build a nuclear bomb since it was signed by the Obama administration in mid-2015, has long rankled Trump and he repeatedly vowed to tear it up.

Trump's decision could ratchet up tensions in the already volatile Middle East, strain relations with U.S. allies in Europe, complicate dealings with Russia and China, and undermine Trump's efforts to get North Korea to give up its nuclear arsenal.

The Iran accord lifted crippling sanctions that had locked Iran out of international banking and the global oil trade. In return, Tehran limited its ability to enrich uranium, reconfigured a heavy-water reactor to block it from producing plutonium, drastically reduced its uranium stockpile and agreed to international inspections and monitoring.

Critics of the deal argue that its inspection provisions are too weak, that its restrictions on enrichment of uranium and nuclear development are time-limited and that the deal did not address Iran's development and testing of ballistic missiles, or its support for militant groups in Yemen, Lebanon and elsewhere in the Mideast.

Supporters say that Iran has abided by the terms and that ending the agreement would cut off the ability of United Nations nuclear inspectors to keep an eye on the potentially dangerous government.

Trump had seemed on the brink of killing the deal in the past, only to pull back at the last minute to give European allies another chance to address his concerns.

French President Emmanuel Macron and German Chancellor Angela Merkel coordinated back-to-back visits to the White House last month to urge Trump to stay in the deal. Trump spoke by phone with Macron early Tuesday to alert him to his decision.

British Foreign Secretary Boris Johnson made his way to Washington on Monday, making his case both on "Fox & Friends," Trump's favorite cable TV show, and in meetings with Vice President Mike Pence and with Pompeo.

U.S. public opinion on the deal varies widely, depending on the poll, in large part because many Americans do not know much about it.

For example, a CBS survey found about 1 in 5 respondents said they want to stay in the deal, with another 1 in 5 wanting to get out and about 3 in 5 saying they lack the information to offer an opinion. Other recent polls show support for the deal ranging between 32 percent and 63 percent.

Even some congressional opponents of the deal urged Trump not to withdraw from it shortly before he appeared at the microphone.

Rep. Ed Royce, the California Republican who heads the House Foreign Affairs Committee, pointed to his own past criticism of the deal, which he has called fundamentally flawed. But he urged Trump to "double down on diplomacy" to fix it. He said tearing up the deal would not reverse Iran's ability to collect its previously frozen assets.

"That toothpaste isn't going back into the tube," he said. "It also won't help galvanize our allies into addressing Iran's dangerous activities that threaten us all. I fear a withdrawal would actually set back these efforts. And Congress has heard nothing about an alternative."

Supporters of the deal had warned that walking away from it could endanger U.S. security and that of allies such as Israel because Iran might try to resume its nuclear program.

The deal "has done an extraordinary job in not only halting but rolling back Iran's nuclear program to ensure that Iran will never get a nuclear weapons," Wendy Sherman, a former U.S. diplomat who helped lead negotiations on the deal in the Obama administration, told reporters Tuesday.

"This is a crisis that Trump is precipitating himself to fulfill a campaign promise and answer his base, without any thought to Plan B," she added.

Withdrawal from the deal "would be a monumental mistake and set (the U.S.) on a collision course in two directions ... with Iran or the allies _ or both," Antony Blinken, a senior member of President Barack Obama's national security team and a former deputy secretary of state, said on the same conference call.

Blinken said ending the Iran deal would complicate Trump's planned nuclear talks with North Korea.

"It makes it less likely to get a yes from North Korea," he said. "Why would North Korea believe anything the United States says when it's willing to rip up a deal that Iran is actually complying with?"

Trump is planning a summit with North Korean leader Kim in coming weeks in hopes of getting him to give up his nuclear arsenal. Most analysts view that task as far more difficult than stopping Iran from someday building a bomb.

It's unclear whether a decision to renege on the Iran deal will affect Trump's ability to negotiate with Kim.