This article has been updated.

After unilaterally withdrawing from the landmark 2015 Iran nuclear accord last year, the Trump administration embarked on a “maximum pressure” campaign against Tehran that was intended to force Iran to abandon many aspects of its expansive foreign policy in the Middle East.

Instead, it appears to be pushing the region toward fresh conflict.

The Trump administration imposed sanctions on Iran that badly damaged the country’s economy. It designated the Islamic Revolutionary Guard Corps, a powerful branch of Iran’s military, a foreign terrorist organization. And more recently, Washington canceled waivers for countries to buy Iranian oil without U.S. penalty.

Iran responded to this increased pressure by threatening to back out of its commitments to the nuclear deal and prevent oil tankers from passing through the Strait of Hormuz.

Tensions had been simmering for weeks when a series of explosions damaged two oil tankers in the Gulf of Oman last Thursday in what the United States has insisted were Iranian acts of sabotage. That allegation has been coolly received by many in the international community, including allies of the United States who say they need to see clearer evidence of a link to Tehran. Meanwhile, Washington announced Monday it plans to send around 1,000 additional troops to the Middle East. And on Thursday, Iran shot down a U.S. naval surveillance drone that U.S. Central Command said was “operating in international airspace over the Strait of Hormuz.” Iran said it was in inside Iranian airspace over the southern province of Hormozgan.

President Trump responded by tweeting that “Iran made a very big mistake!”

On Friday, Trump acknowledged that he ordered a retaliatory strike against Iran, then canceled the mission when he learned that up to 150 people could be killed.

Here’s a timeline of how the crisis escalated over the past eight days:

June 13: Two tankers attacked in Gulf of Oman; Pompeo blames Iran

On Thursday, explosions damaged Japanese- and Norwegian-owned tankers in the Gulf of Oman. Washington quickly blamed Iran.

Speaking to reporters that afternoon, Secretary of State Mike Pompeo said the United States had intelligence to prove that the attacks were carried out by Iran. And he called the strikes “only the latest in a series of attacks instigated by the Islamic Republic of Iran and its surrogates against American and allied interests.”

Pompeo went on to describe five incidents between mid-May and mid-June that he said the United States had determined were part of “an unacceptable campaign of escalating tension by Iran.” The list included attacks on four commercial ships near the Strait of Hormuz, armed drone attacks on oil pipelines in Saudi Arabia, a rocket landing near the U.S. Embassy in Baghdad, a car bomb claimed by the Taliban that wounded four U.S. service members and killed four Afghans in Kabul, and a missile that struck the arrivals terminal of a Saudi airport. The claim that Iran was behind the attack in Kabul — which was claimed by Taliban insurgents — puzzled regional experts who said it would be highly unusual for Iran to launch an attack on U.S. forces in the Afghan capital.

That evening, U.S. Central Command released video it claimed proved Iran was involved in the tanker attacks. As The Post’s Anne Gearan and Carol Morello reported, the U.S. military says the grainy video “shows a small Iranian ship sidling up to a damaged tanker and people on the smaller vessel removing an unexploded mine from the larger ship’s hull.”

June 14: Owner of Japanese tanker offers a different account; Washington weighs response

On Friday, Pentagon officials huddled to determine their response to what they saw as a brazen Iranian attack on the two petrochemical tankers and weighed sending thousands of troops to the region.

Meanwhile, American allies expressed concern that Washington was jumping to conclusions over who was behind the tanker attacks. German Foreign Minister Heiko Maas called the video footage “not enough.”

“We can understand what is being shown, sure, but to make a final assessment, this is not enough for me,” he told reporters in Oslo.

June 15: UAE calls earlier attack ‘state-sponsored’

On Saturday, United Arab Emirates Foreign Minister Abdullah bin Zayed al-Nahyan said his own government has determined that a May attack on vessels off his country’s coast was “state-sponsored,” but he stopped short of saying which country was responsible.

June 16: Pompeo says ‘no doubt’ Iran behind tanker explosions

On Sunday, Pompeo appeared on CBS and Fox News, where he said that there was “no doubt” that Iran was behind the explosions in the Gulf of Oman.

“The intelligence community has lots of data, lots of evidence,” he said. He also doubled down on the claim that Iran was involved in the Taliban-claimed attack in Kabul.

Earlier in the day, Saudi-owned newspaper Asharq al-Awsat released an interview with Saudi Crown Prince Mohammed bin Salman, in which he said he believed Iran was behind the attack. He said Saudi Arabia does not want war with Iran but “will not hesitate to deal with any threat to our people, sovereignty and vital interests.”

June 17: Iran threatens to speed up uranium production as E.U. urges restraint

Under the 2015 nuclear deal, Iran agreed to significantly reduce its uranium-enrichment program, cutting its centrifuges from 19,000 to 6,000 and its stockpiles of enriched uranium from 10,000 kilograms to 300. But on Monday, Iran said that in 10 days it would surpass the previously imposed 300-kilogram limit, alarming Washington and its allies. (My colleague Rick Noack breaks down the details of the 2015 deal in this helpful explainer.)

European leaders urged calm on Monday, with the European Union’s foreign policy chief, Federica Mogherini, saying that “Iran has been compliant with its nuclear commitment as we had expected it to be.” She said the E.U. will wait for a report from the International Atomic Energy Agency before taking action.

“The maximum restraint and wisdom should be applied,” Mogherini said, according to the Associated Press.

Meanwhile, Vasily Nebenzia, Russia’s ambassador to the United Nations, accused Washington of “aggressive, accusatory rhetoric and artificially fueling anti-Iranian sentiment.”

After Iran announced that its stockpile of enriched uranium would grow beyond earlier agreed-upon limits, the Pentagon announced plans to send about 1,000 more troops to the Middle East “for defensive purposes to address air, naval, and ground-based threats.”

June 18: Pompeo says Trump doesn’t want war; Shanahan resigns

Pompeo visited U.S. Central Command headquarters in Tampa on Tuesday, where he insisted the United States “does not want war” but will retaliate if attacked. “We are there to deter aggression,” he said.

As The Post reported on Tuesday, U.S. officials have said Pompeo has “privately delivered warnings intended for Iranian leaders that any attack by Tehran or its proxies resulting in the death of even one American service member will generate a military counterattack.”

Meanwhile, in Washington, Patrick Shanahan, who spent the last five months as acting secretary of defense, abruptly withdrew from consideration for secretary in the midst of widespread criticism prompted by news reports about an earlier domestic dispute. Trump announced that Shanahan was withdrawing “so that he can devote more time to his family.” This week, Shanahan spoke at length with The Washington Post about the incidents.

June 19: Iranians express concern conflict will break out

The Post reported on Wednesday that many Iranians fear hawkish hard-liners in the United States and Iran will push the two countries toward war.

June 20: Iran shoots down U.S. drone, Washington and Tehran offer different accounts

On Thursday, one week after the two tanker explosions, Iranian and U.S. officials said Iran shot down a U.S. drone, although they offered contradictory accounts of where it happened. Iran insisted it occurred over Iranian airspace, with Iran’s Revolutionary Guard Corps saying in a statement that the drone was on its way toward Iran’s Chabahar port “in full secrecy, violating the rules of international aviation.”

In a statement, a Centcom spokesman, Navy Capt. Bill Urban, said that an RQ-4A Global Hawk was shot down early Thursday “in international airspace over the Strait of Hormuz.” As my colleagues Erin Cunningham and Dan Lamothe reported, the RQ-4 is a large and expensive drone, valued at more than $100 million and with a wingspan of 131 feet.

“Iranian reports that the aircraft was over Iran are false,” Urban said. “This was an unprovoked attack on a U.S. surveillance asset in international airspace.”

Trump tweeted that “Iran made a very big mistake!”

June 21: Trump confirms he ordered attack on Iran but called it off

One day after Iran shot down a U.S. drone over the Strait of Hormuz, Trump acknowledged on Twitter that he had ordered the U.S. military to retaliate. It was only when he learned the planned strike could cause up to 150 deaths that he called it off, he said. The New York Times first reported on the decision to order and then cancel the strike.

“We were cocked & loaded to retaliate last night on 3 different sights when I asked, how many will die,” Trump tweeted. “150 people, sir, was the answer from a General. 10 minutes before the strike I stopped it.”

Meanwhile, the Revolutionary Guard’s aerospace commander said Iran sent a number of warnings to the drone before striking it. “When it did not redirect its route and continued flying toward and into our territory, we had to shoot it at 4:05 a.m.,” he said in an interview with Iranian state media. “Our national security is a red line.”

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