President Donald Trump seems to be talking himself into a fateful new chapter of America’s bitter duel with the Iranian Islamic Republic.

The rationale for US military strikes to help Iran’s protesters at a crisis moment for the theocratic regime is becoming more urgent and compelling by the hour.

Trump keeps creating new red lines after Iran’s leaders defied his earlier warning that if they started shooting, he would too. The president warned in a CBS News interview Tuesday that if Iran executed protesters as planned, he would take “strong action.” This does not lock in a US military response. But any combat operations that look merely symbolic could drain his authority to deter with Tehran.

“The president told the Iranian people that help is on the way. And therefore, I think it’s incumbent on the president to take some action here,” Leon Panetta told CNN News Central on Tuesday. The former US defense secretary and CIA director didn’t specify the need for a full-on military attack. But he added: “I think United States credibility right now requires that the United States does something to show support for the protesters.”

The humanitarian case for action is also growing. An internet blackout is still obscuring the full horror of an authoritarian crackdown. But emerging footage suggests carnage. A reported 2,400 people are dead. If the regime survives, many will second-guess powerful outsiders who stood and watched.

Trump’s repeated warnings may also have raised expectations among protesters risking their lives. A president who recently said the only curb on his power overseas was his “morality” might perceive a moral obligation to act.

“I counted today that on seven occasions over the last two weeks, President Trump has threatened to take military action against Iran if it killed peaceful protesters,” Karim Sadjadpour, one of the most prominent US-based Iran experts, told CNN’s Erin Burnett. “That was over 2,000 deaths ago … I do think that many took his words seriously and are hoping for, at a minimum, an American shield to help protect them against this very brutal regime,” said Sadjadpour, of the Carnegie Endowment for International Peace.

There are tantalizing strategic reasons why Trump may look to nudge history.

► Iran’s clerical dictatorship has rarely been as weak, at home or abroad. Wrenching economic shortages mean it’s struggling at the basic task of feeding its people. Desperation is a powerful organization force for protesters.

► Supreme Leader Ayatollah Ali Khamenei is 86, and a destabilizing succession drama is unfolding separate from recent unrest and raising the possibility of a new political dawn.

► Significant numbers of Iran’s top leaders and military and intelligence supremos were wiped out during Israel’s 12-day war with Iran last year.

► And a war on multiple fronts following the October 7, 2023, attacks by Hamas on Israel crippled Iran’s regional clout and capacity to strike back against Israel or US regional bases in revenge for US military action.

So why wouldn’t the United States exploit a chance to end a regime that killed thousands of Americans, including in the Beirut embassy bombing in 1983 by its proxies, and by militias that targeted US troops for years in Iraq?

A Middle East freed of the Islamic regime’s destabilizing influence would make Israel safer and promote Trump’s vision of a wealthy, peaceful and integrated region, which he laid out last year in Saudi Arabia.

A president who prides himself on boldness and ignoring the limits that previous presidents imposed upon themselves must be sorely tempted to take the shot.

After all, he’s been on a roll and is getting a taste for action. He’s fresh off a daring US military raid that grabbed Venezuelan dictator Nicolás Maduro from his bed with no American combat deaths. He loves recalling the round-the-world stealth bombing raid that severely damaged Iran’s nuclear sites last year.

Trump is also hearing from his hawkish friends that greatness beckons. “This is President Trump’s Ronald Reagan moment on steroids,” South Carolina Republican Lindsey Graham wrote on X. “(Iran) will be his Berlin Wall moment a thousand times over.”

Trump met top administration national security officials Tuesday after a trip to Michigan. Asked what he’d do about Iran, the president, in a white baseball cap emblazoned with the letters USA, kept everyone guessing. “I can’t tell you that. I know exactly what it would be.”

But eventually, presidential threats must be backed up by the use of force if future belligerence is to mean anything. Many former officials and foreign diplomats have concluded that President Barack Obama’s failure to enforce his red line against Syria’s use of chemical weapons in 2013 emboldened US adversaries, including Russia in its aggression in Ukraine and Syria.

But history echoes with ill omens.

Rationales for US military interventions from Vietnam to Iraq and Afghanistan to Libya often looked sound from Washington. But the world and US enemies get their own say. And the aftermath of the use of US force is rarely as clean as presidents expect. Trump knows this better than anyone — he probably would never have been president but for Americans’ exhaustion over forever wars in Iraq and Afghanistan.

This jinxed history points to two questions not getting much attention in Washington, which is again experiencing war fever.

► Is there a good reason to believe that new US strikes on Iran would help the protesters and further their hopes of crashing the regime?

► Or could they intensify the backlash against the counter-revolution?

Previous administrations wrestled with this dilemma.

During the 2009 Green Movement protests in Iran, then-President Obama trod cautiously — angering GOP critics — because he wanted to avoid giving Iranian authorities an excuse for brutality. He called for free speech, dissent and a democratic process. But he also said, “It is up to Iranians to make decisions about who Iran’s leaders will be.” He added that he wanted “to avoid the United States being the issue inside of Iran” and becoming a “handy political football.”

Presidents, like the rest of us, can’t know exactly how their decisions will play out. In hindsight, Obama has regrets. He told the “Pod Save America” podcast in 2022 that “every time we see a flash, a glimmer of hope, of people longing for freedom, I think we have to point it out. We have to shine a spotlight on it. We have to express some solidarity about it.”

The 44th president was not suggesting he’d have staged military strikes — that was unthinkable with the US stuck in quagmires in Iraq and Afghanistan. But presidents have plenty of other options.

Trump, with his blunt language, love of threats and aversion to detail, often exacerbates superficiality in Washington debates.

The situation in Iran is deeply complex. He can’t just bombard Iran into a democracy. He might not be able to even do enough damage to protect demonstrators. Cyberattacks might thwart the command-and-control capacity of regime security forces. But can US air power really save protesters who are being gunned down in the streets by Basij internal security forces charged with enforcing theocratic rule?

The daring special forces raid into Venezuela that removed Maduro seems unlikely to be repeated in Iran, where the risks of inserting US personnel in a regime decapitation strike appear prohibitive. US or Israeli missile or drone strikes could do the job. But eradicating Iran’s religious leaders might simply empower a hardline secular strongman.

Despite the sudden prominence of exiled dissident Reza Pahlavi — the scion of the last shah of Iran, who was ousted in the 1979 Islamic Revolution — there are few signs of credible opposition forces in Iran that could lead a transition. And generations of meddling by imperialist powers such as Britain, Russia and the US in Iran show that outsiders can’t chart its future.

Iran, unlike many Middle Eastern states, is not a creation of colonialist mapmakers. Its enduring Persian civilization and national identify might spare it the agony of Syria’s splintering. But a breakdown of authority is possible if a regime that has ruled repressively since 1979 is ousted. Any subsequent refugee flows and instability would not be welcomed by US regional allies, as much as they’d hail the Shiite revolutionary regime’s demise.

Then there’s the issue of US capacity. Naval forces are stretched by the massive armada Trump has deployed off Venezuela. Many military aircraft are stationed at US bases throughout the Middle East. But according to the US Naval Institute nonprofit, the nearest aircraft carrier strike group is with the USS Abraham Lincoln in the South China Sea.

It’s also fair to ask just how much one administration can take on. Trump just seized Maduro, a Western Hemisphere dictator; he’s demanding the US take ownership of Greenland; he’s supposed to be running Gaza under his Israel-Hamas peace plan. The White House loves spectacular foreign policy wins but seems to be lacking on follow-through.

There’s also a head-spinning contradiction in Trump apparently pushing for democracy in Iran while sidelining the democratic opposition in Caracas after ousting Maduro. Yet recent history and the weight of his rhetoric suggest he might find it impossible to deny his love of action.

But he’d be taking another huge risk.

A reporter asked the president Tuesday if he could be sure that US air strikes would protect protesters. “Well, you never know, do you,” he replied.

“So far, my track record has been excellent, but you never know.”