Over the past two decades, the United States has used sanctions, sabotage, cyberattacks and diplomatic negotiations to try to slow Iran’s long march to a nuclear weapon.

At roughly 2:30 a.m. Sunday in Iran, President Trump unleashed a show of raw military might that each of his last four predecessors had deliberately avoided, for fear of plunging the United States into war in the Middle East.

After days of declaring that he could not take the risk that the mullahs and generals of Tehran who had survived Israel’s strikes would make a final leap to a nuclear weapon, he ordered a fleet of B-2 bombers halfway around the world to drop the most powerful conventional bombs on the most critical sites in Iran’s vast nuclear complexes.

The prime target was the deeply buried enrichment center at Fordo, which Israel was incapable of reaching.

For Mr. Trump, the decision to attack the nuclear infrastructure of a hostile nation represents the biggest — and potentially most dangerous — gamble of his second term.

He is betting that the United States can repel whatever retaliation Iran’s leadership orders against more than 40,000 American troops spread over bases throughout the region. All are within range of Tehran’s missile fleet, even after eight days of relentless attacks by Israel. And he is betting that he can deter a vastly debilitated Iran from using its familiar techniques — terrorism, hostage-taking and cyberattacks — as a more indirect line of attack to wreak revenge.

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