Iran expanded its stockpile of low enriched uranium beyond the nuclear deal’s limit of 300 kilograms, conducted research that could enable it to build more advanced centrifuges, exceeded the previous limits on the level of enrichment, and started operating centrifuges in a hardened bunker near the city of Qom — but it stopped short of exiting the agreement entirely.

All of these steps have been reversible, since the Iranians hoped they would either force President Trump to accept a new deal that would lift the American sanctions on Iran — he seemed to consider that seriously when he came close to meeting with President Hassan Rouhani of Iran last September — or get European leaders to provide financial compensation. Now any such deal seems impossible.

The resumption of previously frozen Iranian nuclear activities — uranium enrichment to the more dangerous level of 20 percent, a significant step toward weapons-grade levels, or resuming construction on the plutonium-producing heavy water reactor could dramatically reduce the time necessary for Iran to acquire the material needed to build a nuclear weapon. The nuclear deal’s restrictions, now abandoned, had established a threshold of at least a year.

Iran’s nuclear expansion would force the Trump administration to either accept the risk that Tehran acquires a nuclear weapons capability — an ironic outcome of leaving the allegedly “bad” nuclear deal — or it will have to conduct military strikes to prevent it and initiate the conflict it claims it wants to avoid.

Iranian leaders understand that a “dash” for a bomb would provoke international opposition and garner support for military strikes. Tehran is likely to take incremental steps and raise the bar for an American response.

Under the nuclear deal, it would have been many years before Iran could increase enrichment, the size of its uranium stockpile or the number of its centrifuges. By destroying a deal that it claimed did not last long enough or impose enough restrictions on Iran’s nuclear program, the Trump administration has created a situation in which Iran may soon end up with no nuclear restrictions at all.

Some Americans may see Iran’s nuclear expansion as an opportunity to take military action against the Iranian regime. When he was a member of Congress, Secretary of State Mike Pompeo argued the United States could “destroy the Iranian nuclear capacity” with “under 2,000 sorties” and it was “not an insurmountable task.”