President Donald Trump’s Iran policy has been rooted in the idea that being tougher on Tehran would yield better results and perhaps even a new nuclear deal to replace the Obama administration pact that he pulled the U.S. out of a year ago Wednesday.

That strategy is now being put to the test as tension escalates between Washington and Tehran, even as both sides appear willing to negotiate an end to the standoff.

Iran threatened to enrich its uranium stockpile closer to weapons-grade levels in 60 days if world powers fail to negotiate new terms for the 2015 nuclear deal. It follows the Trump administration’s “maximum pressure” campaign of diplomatic and economic measures that have exacted a punishing toll on the Islamic Republic.

The effort has been a success in the view of the president and senior officials of his administration.

“Because of our action, the Iranian regime is struggling to fund its campaign of violent terror, as its economy heads into an unprecedented depression, government revenue dries up and inflation spirals out of control,” Trump said Wednesday as he announced yet another round of sanctions, this time targeting the country’s metals industry.

The test is whether Iran will return to the bargaining table and agree to the new terms set by the Trump administration. The stakes couldn’t be higher, as shown by the U.S. decision over the weekend to rush an aircraft carrier group and other military assets to the Middle East to confront an unspecified Iranian threat.

Democrats used Iran’s announcement as an opportunity to criticize Trump for withdrawing from the deal. Sen. Chris Murphy, D-Conn., called it a sign of “blind, meandering, escalatory” foreign policy.

“Iran’s moves to restart their nuclear program are a direct consequence of the Trump administration withdrawing from the Iran deal,” said Murphy, a member of the Senate Foreign Relations Committee.

Despite Iran’s announced deadline to pull out of the remainder of the nuclear deal, there have been signs that Tehran is willing to talk. Foreign Minister Javad Zarif said during a visit to New York last month that he thinks Trump wants to deal but is trying an antagonistic approach at the direction of senior aides and Middle Eastern allies.

“Try the language of respect,” he urged him, pretending to address the president directly. “It won’t kill you, believe me.”

Trump himself says he’s ready to talk. “We call on the regime to abandon its nuclear ambitions, change its destructive behavior, respect the rights of its people and return in good faith to the negotiating table,” he said in announcing the new sanctions.

Brian Hook, U.S. envoy to Iran, told reporters at the State Department that the U.S. laid out 12 demands last year for a new Iran deal and an end to the Trump administration’s maximum pressure campaign. They include an end to all uranium enrichment, ceasing all support for militant groups in the Middle East and the release of all U.S. citizens detained in Iran on what the administration considers illegitimate grounds.

The United States, Germany, Britain, France, Russia, China and the European Union signed the 2015 deal with Iran, which lifted international sanctions in exchange for Tehran limiting its nuclear program, including restricting uranium enrichment for 10 years.

On May 8, 2018, Trump pulled out of the agreement, which he called “the worst deal in history.” He said the accord should also have restrained Iran’s ballistic missile program and curbed Tehran’s malign activities in the region and support for terror networks. The administration then re-imposed the sanctions on Iran that had been lifted when the agreement went into force.

The administration sees its move as a success.

Deprived of much of its oil revenue, Iran cut its overall military spending by 28% after reaching a peak in 2017, Hook said. Inflation has risen in the Islamic Republic and the economy is in recession, forecast to shrink by 3%, while global oil prices haven’t budged even as Iranian crude has been largely taken out of the market, production at a historic low.

“We have made our focus around diplomatic isolation and economic pressure,” he said. “That policy is working.”

The other nations who signed the nuclear deal negotiated by the Obama administration have remained in the pact and have tried to provide Iran with enough economic incentives to keep the agreement alive.

Complaining that it has not reaped the economic benefits it expected from signing the deal, Iran on Wednesday threatened to enrich its uranium stockpile closer to weapons-grade levels in 60 days if world powers fail to negotiate new terms. Iran stopped its sale of excess uranium and heavy water as a first step — something required under the deal. In 60 days, if no new deal is in place, Iran said it would increase its enrichment of uranium beyond 3.67%, which is permitted by the accord.

“Zarif today is doing what Zarif does very well, which is setting the table for negotiations because I think the Iranians are now realizing that they may not be able to wait Trump out,” said Mark Dubowitz, chief executive of the Foundation for Defense of Democracies and a critic of the deal.

“The economy is in such bad shape and getting worse that they may experience a massive economic crisis before January 2021,” when either Trump starts a second term or a new American president takes office. “I think Zarif can’t wait to get back to the table,” Dubowitz said.

The heightened tension over Iran’s nuclear program comes just after the U.S. dispatched the USS Lincoln aircraft carrier and bombers to the Persian Gulf in response to intelligence reports warning Iran was going to strike U.S. assets, interests or allies.

Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, told a Senate appropriations subcommittee Wednesday that intelligence threats the U.S. began receiving last week “really intensified” by the end of the week. He said the U.S. “sent some messages” to Tehran, but did not provide any details.

Traveling in London, Secretary of State Mike Pompeo issued a restrained response to Iran’s announcement. He said America “will wait and observe” what Iran does next. “They have made a number of statements about actions they have threatened to do in order to get the world to jump,” Pompeo said.

Tim Morrison, senior director for weapons of mass destruction under national security adviser John Bolton at the White House, was more critical of Iran’s threat to violate the nuclear deal. “Let’s be clear,” he said. “This is nothing less than nuclear blackmail.”

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