The Obama administration’s definition of diplomacy with Iran is that it does not talk about “regime change.” Instead it talks about “tightening the noose.”

As the rial collapses and Iranians die because they can’t afford life-saving medicines, no doubt they feel deeply grateful for America’s kind attention.

The Washington Post reports: At a time when U.S. officials are increasingly confident that economic and political pressure alone may succeed in curbing Iran’s nuclear ambitions, the mood here has turned bleak and belligerent as Iranians prepare grimly for a period of prolonged hardship and, they fear, war.

This stark contrast has been evident in the Iranian capital this week as a top military commander declared a “critical point” in the country’s long feud with the West and ordinary Iranians stocked up on essential supplies. Merchants watched helplessly as the Iranian currency, the rial, shed more than a third of its value, triggering huge increases in the prices of imported goods.

“I will tell you what this is leading to: war,” said a merchant in Tehran’s popular Paytakht bazaar who gave his name only as Milad. “My family, friends and I — we are all desperate.”

The sense of impending confrontation is not shared in Washington and other Western capitals, where government officials and analysts expressed cautious satisfaction that their policies are working.

Former and current U.S. government officials did not dismiss the possibility of a military confrontation but said they saw recent threats by Iranian leaders — including warning a U.S. aircraft carrier this week not to return to the crucial Strait of Hormuz — mainly as signs of rising frustration. U.S. officials say this amounts to vindication of a years-long policy of increasing pressure, including through clandestine operations, on Iran’s clerical rulers without provoking war.

“The reasons you’re seeing the bluster now is because they’re feeling it,” said Dennis Ross, who was one of the White House’s chief advisers on Iran before stepping down late last year. With even tougher sanctions poised to take effect in weeks, the White House had succeeded in dramatically raising the costs of Iran’s nuclear program, he said.

“The measure, in the end, is, ‘Do they change their behavior?’ ” Ross said.

The Obama administration is readying new punitive measures targeting the Central Bank of Iran, while leaders of the European Union took a step this week toward approving strict curbs on imports of Iranian petroleum in hopes of pressuring the nation to abandon what they say is a drive to develop nuclear weapons. Iran says its nuclear program is for peaceful energy production.

State Department spokes­woman Victoria Nuland deemed as “very good news” the E.U.’s commitment to shutting off the flow of Iranian oil to Europe.

“This is consistent with tightening the noose on Iran economically,” Nuland told reporters Wednesday. “We think that the place to get Iran’s attention is with regard to its oil sector.”

In Tehran, that tightening is being felt by millions of people. Economists and independent analysts say the sanctions have aggravated the country’s chronic economic problems and fueled a currency crisis that is limiting the availability of a broad array of goods, including illegally imported iPhones and life-saving medicines.