A year ago, Iranians poured into their streets to denounce ­Supreme Leader Ali Khamenei and call for an end to his brutal ­regime. Protests have continued ­unabated since, though these are smaller in number and less visible to foreign ­media.

The Tehran regime’s grip on power is no firmer now than it was then. Still entrenched and viciously clinging to life, the Islamic Republic is nevertheless more vulnerable than it has ever been since the 1979 revolution.

Today, unpaid factory workers, teachers, farmers and truck drivers are some of the most organized and motivated anti-regime forces. The southwestern city of Ahvaz experienced anti-regime labor protests last month. Truck drivers were also on nationwide strikes for much of 2018, blocking major roadways and access to gas stations over low pay and rising tolls.

Farmers in Isfahan, in central Iran, have turned their backs against regime clerics during Friday prayers and chanted: “Our back to the enemy, our faces to our nation.” Another favorite slogan: “They say our enemy is America, when the real enemy is right here” — meaning the mullahs. Meanwhile, many Iranian women have been shedding the compulsory hijab in public, a gesture that was unthinkable even two years ago.

The sources of popular anger vary, from water shortages to economic collapse to frustration with social restrictions. Most important, recent years disabused Iranians of the illusion of “reform” peddled by so-called moderates like President Hassan Rouhani. The people have learned that such rhetoric only masks the country’s environmental, economic and social devastation ­under the mullahs.

The Islamic Republic’s demise has been predicted many times, of course. Iran’s theocracy has survived tough challenges before, from the Iran-Iraq War of the 1980s to the massive Green uprising that followed 2009’s fraudulent presidential “election.” But today the ­regime confronts a crisis without precedent, owing to the sheer breadth of social discontent.

Even insiders such as former President Mahmoud ­Ahmadinejad believe that the ­Islamic Republic may soon face a complete revolution.

Senior cleric Ayatollah Abdollah Javadi-Amoli recently expressed fears of a popular revolt that “will push us” — that is, the clergy — “into the sea.” Faezeh Hashemi, the “moderate” daughter of one of the regime’s founders, has described the ­Islamic Republic as a “failed” theocratic system.

Still, the Islamic Republic enjoys a core base of support among the population, sustained with ideological indoctrination and financial and political ­patronage.

Moreover, Khamenei, the supreme leader, still retains control over the fearsome security apparatus, including the Revolutionary Guards and the basij paramilitary forces. The people are outgunned, and while it is ultimately up to them to bring fundamental change to Iran, Washington has an important role to play.

Instead of seeking to tweak the Islamic Republic’s behavior, the US should strongly and unequivocally support the Iranian people’s right to self-determination. President Trump shouldn’t engage the regime diplomatically, or lift sanctions, until the mullahs permit peaceful demonstrations and ­respect the right to organize political parties that favor a free, secular and democratic Iran.

The US should also focus on combatting the regime’s propaganda machine by creating new Persian-language media that ­bypass the aging and ineffective Voice of America and Radio Farda, US-taxpayer-funded outlets that too often broadcast the regime’s worldview to Iran.

Private TV broadcasts, such as the enormously popular Manoto TV based in London, can be a powerful tool in strengthening US interests in Iran.

Likewise, America should provide moral and material assistance to domestic forces combatting the regime. Washington should pursue some of the same policies that proved successful in defeating Communism during the Cold War, such as clandestine aid to Solidarity in Poland.

The Islamic Republic will never change for the better. The Iranian people are awake to this reality. Whatever the wisdom of Trump’s recent Syria pullout, America and its interests in the region will never be safe until Khamenei’s ­regime is gone. Washington’s best allies are the Iranians bravely fighting injustice every day.

Alireza Nader is founder and CEO of New Iran, a nonprofit and nonpartisan advocacy organization in Washington.