Saturday’s attack on Abqaiq, home to one of the most important petroleum processing facilities in Saudi Arabia, threatens to dramatically escalate tensions in the Persian Gulf. While the Saudis have not yet attributed blame, they are likely to do so soon — and to react accordingly. Secretary of State Mike Pompeo has declared what most observers suspect: The Iranians might not have directly orchestrated the attacks but are almost certainly behind them.

If true, Iran is continuing its response to the administration’s “maximum pressure” campaign with its own version of maximum pressure. The Iranians have long declared that if they cannot export their oil, others won’t be able to do so either. In May, just weeks after President Trump decided to add to existing sanctions with the aim of reducing Tehran’s oil exports to zero, the Iranians began their “deniable” assault on oil supplies out of the area, twice attacking oil tankers and using proxies in Yemen and Iraq to attack Saudi oil facilities.

Using proxies and denying responsibility for such attacks is the Iranian way of reducing the risks of such actions. And the U.S. response to date has persuaded Supreme Leader Ayatollah Ali Khamenei that the risks of what the Quds Force of the Revolutionary Guard is doing are manageable. After all, when Trump declared that we don’t get our oil out of the Persian Gulf, so others should bear the main responsibility for keeping the Strait of Hormuz open, he reversed the policy of every president since Jimmy Carter — who declared the Persian Gulf a vital national security interest of the United States in January 1980.

We might well be on the precipice of the first foreign policy crisis of the Trump administration. Trump will face a real dilemma: He will not want oil prices to shoot up, and he will not want to get embroiled in a war with Iran. There are several steps he should take:

First, it is good that Trump is prepared to open the strategic petroleum reserve. But the release needs to be significant, at least 100 million barrels, not only to hold down oil prices but to show the Iranians that we can prevent them from immediately squeezing the international community on the oil supply.

Second, the secretary of state must work immediately to get the Europeans to declare that they will have little choice but to reimpose sanctions on Iran if there are further such attacks. Until now, European fear of escalation and conflict — and distrust of what we might do — has kept them from holding the Iranians responsible for the earlier attacks on tankers. This time, however, Pompeo is in a position to say credibly that non-action will make a conflict inevitable.

Third, Trump should call Russian President Vladimir Putin and ask him to pass a message to Khamenei: If the attacks don’t stop, we will take military steps to stop them. Putin wants to be seen as the arbiter of events in the region and does not want U.S. power again to look decisive. The supreme leader won’t ignore what Putin conveys. With the Chinese dependent on oil from the region, they, too, should be approached to pressure the Iranians as part of the campaign to show Khamenei the Revolutionary Guard’s aggressive policy is becoming far too dangerous.

Fourth, because Saudi Arabia might feel it must react to protect its territory and to show that Iran cannot engineer such attacks with impunity, the administration must now offer additional means to be able to blunt and counter such attacks. In addition, if it does not want the Saudis to react militarily, it will need to show we can affect Iran’s behavior. Trump’s call to Crown Prince Mohammed bin Salman Saturday was no doubt designed to provide reassurance. But we will still have to demonstrate that we can stop the Iranian attacks or at least offer better protection against drone attacks than the Saudis presently have.

Lastly, it is essential that the Iranians fear the consequences of their actions now and that they lack plausible deniability for them. The problem is that our maximum pressure is putting the Islamic Republic in a corner economically but not politically or militarily. The supreme leader does not believe there is much to be lost unless the United States is prepared to lift the sanctions on Iran — or to actually carry out military strikes against it.

Striking the balance between threats and offering the Iranians a way out is the challenge before the administration now. One possibility might be for the administration to propose that the French host a meeting of the parties to the Iran nuclear deal — the five permanent members of the U.N. Security Council, as well as Germany and the Iranians — with the aim of discussing the Iranian nuclear program and the regional dangers. True, there is a risk that the United States will come under pressure to rejoin the nuclear deal or drop sanctions, but the Iranians and the other participants should also know that if this fails, a dangerous escalation could be the result.

Regardless, if Trump is to avoid a crisis that might soon spin out of control, he will have to act soon.

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