BIDEN ADMINISTRATION officials have been saying that the process of restoring the nuclear agreement with Iran, which President Donald Trump ruptured in a failed attempt to force the Islamic republic to capitulate or collapse, would be long and complicated. Just how much so was underlined over the weekend with Israel’s latest attempt at sabotage — of Iranian nuclear facilities, and perhaps of U.S. diplomacy.

A blackout Sunday at the Natanz plant for uranium enrichment, caused by an explosion, appears to have inflicted damage just as Iranian technicians were bringing new, more advanced centrifuges online. How much damage wasn’t clear: While the New York Times quoted intelligence sources as saying operations at Natanz could be set back for nine months, a senior Iranian official said Monday that enrichment “has not stopped and is moving forward vigorously.”

Notably, the Mossad intelligence agency told Israeli media it was responsible for the attack, while senior U.S. officials quickly made it clear that Washington was not involved. Those unusual clarifications came on a day when the first senior Biden administration official to visit Israel, Defense Secretary Lloyd Austin, was meeting with Prime Minister Benjamin Netanyahu. Mr. Netanyahu has loudly opposed any U.S. return to the nuclear accord, and recent Israeli actions could be seen as aimed to make it more difficult. On the same day that multilateral talks on a settlement began in Vienna last Thursday, another Israeli attack struck an Iranian arsenal ship in the Red Sea.

It’s possible that this low-grade warfare — Iran has also targeted Israeli ships — will give the Biden administration more leverage in the negotiations, in which it is seeking a reversal of the stepped-up enrichment and other nuclear activities Tehran launched in response to Mr. Trump. But the past week has underlined a sharp divergence in U.S. and Israeli interests. For Israel, permanent conflict with Iran is a given, no detente is conceivable and military attacks that set back the nuclear program for a few months are the best that can be hoped for. The United States, in contrast, succeeded in striking a deal with Tehran that effectively removed the threat that it would produce nuclear weapons for at least a decade. If the Biden administration can restore the accord, it will be freer to remove military assets from the Middle East and focus on the rising challenge of China.

Up until the weekend, the U.S. initiative appeared to be progressing. All sides called the Vienna talks, which include European governments as well as Russia and China, “constructive,” and Iran offered a goodwill gesture by releasing a South Korean ship it had been holding. The regime of Ayatollah Ali Khamenei has much to gain from a deal, including $30 billion in frozen assets and renewed access to world oil markets. But its internal politics, as always, are complicated: The relatively moderate government that negotiated the 2015 deal will soon leave office, and elections in June could empower more hard-line leaders.

Mr. Biden, who already faces bipartisan opposition in Congress to a new deal with Iran, doesn’t have much room to pressure Mr. Netanyahu for restraint, though he should try. Meanwhile, Mr. Biden should persist with his diplomatic strategy — and hope that the Iranian regime chooses to make a distinction between Israel and the United States.

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