WASHINGTON The attacks on two tankers in the Gulf of Oman on Thursday have again sent the United States and Iran, two longtime adversaries, hurtling toward potential crisis. The challenges are diplomatic and economic, as well as military.
But that course was set a year ago, foreign policy experts say, when President Trump, enforcing his maximum pressure campaign against Tehran, withdrew the United States from an Obama-era agreement meant to rein in Irans nuclear ambitions. Tehran did not immediately retaliate in the months after, but as increased American pressure and sanctions have put a strangle on its economy, Iran may now be hitting back.
Iran was getting repeatedly punched in the face by the Trump administration, and theyve been warning for months there will be consequences, said Karim Sadjadpour, an Iran expert at the Carnegie Endowment for International Peace. The Iranian economy has long been riddled by endemic mismanagement, corruption, cronyism, and brain drain. Sanctions makes all these problems worse.
Heres a look at how the United States turned up the pressure on Iran.
Mr. Trump made good on his campaign promise, and announced that he was withdrawing the United States from the Iran nuclear deal, dismantling the signature foreign policy achievement of President Barack Obama. Mr. Trump said that the United States would reimpose the stringent sanctions it had on Iran before the deal and would consider new sanctions against it.
The nuclear deal had tightly restricted Irans nuclear ambitions in return for ending sanctions that had crippled its economy.
The other signatories to the deal, France, Germany, Britain, Russia and China, said they would remain in the agreement. But Mr. Trump put allies on notice that European companies would face American sanctions if they did business with Iran, and would have to choose between the United States and Iran.
This was a horrible one-sided deal that should have never, ever been made, Mr. Trump said. The decision drew a public rebuke from Mr. Obama, who warned that the American withdrawal would leave the world less safe, forced to face a losing choice between a nuclear-armed Iran or another war in the Middle East.
President Hassan Rouhani of Iran said that his country would continue to abide by the terms of the deal. He criticized Mr. Trump for pulling out of the pact as well as other international treaties.
Mr. Trump, over the objections of Pentagon officials, announced that he was designating a powerful arm of the Iranian military, its Islamic Revolutionary Guards Corps, as a foreign terrorist organization.
It was the first time that the United States named part of another countrys government as that type of official threat. The designation imposed wide-ranging economic and travel sanctions on the group, which carries out operations across the Middle East, trains Arab Shiite militias and oversee businesses in Iran. The sanctions also applied to organizations, companies and individuals with ties to the Revolutionary Guards.
The designation, which went into effect April 15, will significantly expand the scope and scale of our maximum pressure on the Iranian regime, Mr. Trump said in a statement.
Gen. Joseph F. Dunford, the chairman of the Joint Chiefs of Staff, opposed the move, arguing that it would allow Iranian leaders to justify operations against Americans overseas, especially Special Operations units and paramilitary units working under the C.I.A. But Secretary of State Mike Pompeo and John R. Bolton, the national security adviser, pushed for it.
Irans Supreme National Security Council said it was designating as a terrorist organization the United States Central Command, which oversees American military operations in the Middle East.
American officials said they began seeing stepped-up threats against their forces in the region, as well as reports that Iranian-backed Shiite militias were considering attacks on American troops in Iraq.
Meanwhile, Irans oil exports fell by more than half since Mr. Trump announced he was pulling out of the nuclear deal, to under one million barrels a day.
Mr. Bolton announced that the United States was sending an aircraft carrier strike group and Air Force bombers to the Middle East because of troubling and escalatory indications and warnings related to Iran.
In a statement released on a Sunday night, Mr. Bolton said that the deployment was intended to send a clear and unmistakable message to the Iranian regime that any attack on United States interests or on those of our allies will be met with unrelenting force.
Four oil tankers were attacked in the Persian Gulf a week later; Mr. Pompeo and Mr. Bolton said Iran was responsible. Two of the tankers belonged to Saudi Arabia and one to the United Arab Emirates; both are adversaries of Iran and allies of the United States. The fourth tanker is owned by a Norwegian company.
One year after announcing he was pulling out of the nuclear deal, Mr. Trump placed a new round of sanctions on Iran, targeting the countrys metals industry, its largest source of nonpetroleum revenue.
Todays action targets Irans revenue from the export of industrial metals 10 percent of its export economy and puts other nations on notice that allowing Iranian steel and other metals into your ports will no longer be tolerated, Mr. Trump said in a statement.
Around that time, the Trump administration also hit Iranian oil exports, by effectively ordering countries worldwide to stop buying oil from the country or face sanctions of their own. Brian Hook, the State Departments special envoy for Iran, said the United States would not grant waivers on sanctions to any countries that buy Iranian oil.
Iran has a choice, Tim Morrison, a White House arms control adviser, told a conference organized by a Washington-based think tank. At some point, even the mullahs will get it.
Iran ramped up its production of nuclear fuel, following through on a threat to begin walking away from the nuclear deal.
Mr. Trump ordered 1,500 additional troops to the Middle East to increase protection of American forces already there. He also circumvented Congress and declared an emergency over Iran, moving ahead with arms sales to Saudi Arabia, the United Arab Emirates and Jordan that had been blocked by Congress since last year.
Gen. Frank McKenzie, the head of United States Central Command, told reporters traveling with him aboard the aircraft carrier Abraham Lincoln in the Persian Gulf this month that because the United States deployed the carrier, Iran may now be recalculating previous plans to attack American interests in the region.
They are looking hard at the carrier because they know we are looking hard at them, Gen. McKenzie said.
Explosions crippled two oil tankers in the Gulf of Oman on Thursday; the United States military released video footage that Central Command said shows a Revolutionary Guards patrol boat pulling up alongside one of the stricken ships several hours after the initial explosion, and removing an unexploded limpet mine in broad daylight. The video, American officials said, proves that Iran was behind the attack.
Crude oil prices rose more than 3 percent, indirectly bolstering Irans revenue as an oil producer.
Helene Cooper is a Pentagon correspondent. She was previously an editor, diplomatic correspondent and White House correspondent, and was part of the team awarded the 2015 Pulitzer Prize for International Reporting, for its coverage of the Ebola epidemic. @helenecooper