Mysterious explosions that crippled two commercial tankers in the Gulf of Oman on Thursday have set off a spike in oil prices, threats from President Trump and calls for calm from the secretary general of the United Nations.
Even though both vessels were evacuated without serious injury, the incident raised immediate alarms about a potential military conflagration among rival powers around the region, and by Thursday night Secretary of State Mike Pompeo had blamed Iran — raising tensions between Washington and Tehran to the highest level in three decades. Iran says it was framed.
What would make two disabled ships set the world on edge? Here are the basics.
Why do these tankers matter?
The explosions, which the United States called deliberate attacks by Iran, may have been a tacit threat to choke off a vital artery of the global economy. The Gulf of Oman leads through the 21-mile-wide Strait of Hormuz into the Persian Gulf, and about a third of the world’s crude oil supplies and nearly a fifth of its natural gas pass through its waters.
Why does the United States police this waterway?
Neither of the ships, both bound for Asia, had any connection with the United States. But Washington has been committed to ensuring the safe export of petroleum from the Persian Gulf since World War II. And since the first gulf war in 1990, the United States has reinforced that commitment with a military buildup in the region. An attempt to close the Strait of Hormuz or otherwise endanger the flow of oil would be a serious threat to American interests — even if no American ships were involved.
Moreover, President Trump has placed a priority on confronting Iran, echoing the complaints of Israel and the Arab Gulf States that Tehran’s activities, in their view, are destabilizing the region. Mr. Trump last year pulled the United States out of a 2015 deal that promised Iran economic benefits for curtailing its nuclear program.
He reimposed old sanctions and added more designed to cripple Iran’s ability to export oil anywhere. He designated part of Iran’s military, its Islamic Revolutionary Guards Corps, as a terrorist group, and he has threatened devastating retaliation if Iran picks a fight with the United States — even “the official end of Iran,” as Mr. Trump put it on Twitter.
Yet the Trump administration has outlined inconsistent goals. At times, its officials have demanded sweeping changes in Iranian policy around the region, where Tehran has spread its influence by backing allied militias in Iraq, Lebanon, Syria, Gaza and Yemen (critics accuse Iran of supporting government opponents in Bahrain as well).
At other times President Trump has appeared to soften those demands.
But the administration may find it difficult to back down this time. Late Thursday night, the Pentagon released a grainy video that officials said showed Iranian mariners removing an unexploded mine from the hull of one of the ships, suggesting the Iranians had placed it there and were trying to remove the evidence. The video may make it harder for the administration to avoid more muscular action.
Iran denies responsibility and says the evidence was planted. Why would it carry out such an attack?
Many experts are questioning the Trump administration’s claims of Iranian responsibility. Still, a consensus has emerged among Western government officials that Iran carried out a similar if less damaging attack last month on four tankers in the same waterway near the Port of Fujairah in the United Arab Emirates.
Experts say Iran may be seeking ways to hit back at Washington while maintaining just enough ambiguity about its role to avoid a direct military counterattack. Harassing tankers in the Gulf punishes the United States by raising the price of oil, and that has the collateral benefit for Iran of boosting its revenue from oil sales.
Former American officials note that Iran has often succeeded in barely hidden or indirect attacks on the United States without incurring punishment. During the American occupation of Iraq after the 2003 invasion, for example, Washington knew that Iran was actively training and equipping Shiite militias that attacked and killed American troops. But the Iranians maintained the militias may have acted on their own. Tehran managed to escape direct retaliation.
“Plausible deniability is a key part of Iran’s modus operandi,” said Ali Ansari, director of the Institute for Iranian Studies at the University of St. Andrews in Scotland.
Power rivalries within the Iranian government may play a role as well. The Islamic Revolutionary Guards Corps can operate independently of the relatively moderate civilian leaders, like President Hassan Rouhani or Foreign Minister Mohammad Javad Zarif. And the Revolutionary Guards leaders are allied with hard-line politicians, who may benefit in upcoming elections from an upsurge in anti-American sentiment generated by the standoff with Washington. So the Revolutionary Guards, if they were responsible, could be striking at Mr. Rouhani as well.
“It is not at all certain that Zarif or Rouhani would know what was going on,” Professor Ansari said. “Zarif could get up and deny it because he may not have been told.”
If this was an Iranian provocation, what makes it different?
The current standoff is taking place in a potentially more volatile context because of the changing leadership of the Arab states around Iran — specifically the rise of Crown Prince Mohammed bin Salman in Saudi Arabia.
Previous Saudi rulers were conspicuously cautious. In 1996, for example, King Abdullah was so afraid of direct conflict with Iran that he deliberately sought to hide the Iranian role in an attack on the Khobar Tower complex that killed 19 United States Air Force personnel. Former American officials involved say that the king worried an American counterattack might embroil the kingdom in conflict as well.
But the ascent of Prince Mohammed, who is now the de facto ruler of the kingdom, has turned up the heat on the longstanding cold war across the waters of the gulf, between Iran on one side and the Arab monarchies on the other.
The two sides have fought for years through surrogate forces in neighboring countries, including Lebanon, Iraq, Syria and Bahrain.
But now Prince Mohammed has ramped up nationalist and anti-Iranian propaganda within the kingdom, while for the first time backing a direct intervention by Saudi forces and their allies from the United Arab Emirates in Yemen, where they are seeking to crush a takeover by the Houthis, a Yemeni faction allied with Iran.
Now, as the United States threatens Iran, its Houthi allies appear to be lashing out at the Saudis. Houthi missiles have hit a Saudi oil pipeline. Another missile hit a Saudi airport this week, injuring 26 people, and on Friday Saudi news media said the kingdom had intercepted more Houthi missiles.
Both Saudi Arabia and the United Arab Emirates lobbied the United States to abandon the nuclear deal with Iran, arguing that the United States should do more to push back against Iranian influence around the region.
Israel, another foe of Iran, made the same argument. Iranian leaders often rail against the Jewish state and provide support for Hamas, the Palestinian militant group that controls Gaza.
But while the Saudis, Emiratis and Israelis have all pushed for Washington to get tougher with Iran, diplomats say, they also have reasons to hope that the exchange of threats stops short of open warfare that entangles their countries. All three are prime targets for Iranian counterattacks in the event of military conflict.
“Having Iran out there as a permanent bête noire, to blame for all the things that go wrong in the region, but without any of the dangers of a shooting war in their neighborhood — that is the ideal situation from the viewpoint of the Saudis, Emiratis and Israelis,” said Paul Pillar, a Georgetown University professor and former C.I.A. official who studies the region.