Are we at war yet? Over recent days, warnings of a gathering storm have been ubiquitous and incessant.

House Intelligence Committee Chairman Adam Schiff said he was “gravely concerned about actions taken by the administration that appear calculated to put us on a collision course” with Iran’s rulers.

Trita Parsi, president of the National Iranian American Council, echoed the charge being made by Iranian Foreign Minister Javad Zarif: “Trump’s potential war with Iran is all John Bolton’s doing.”

Wendy Sherman, a senior diplomat in the Obama administration, published a piece in The New York Times headlined: “How to Stop the March to War With Iran.” She, too, urged that something be done to “halt John Bolton, President Trump’s national security adviser, in his long-held ambition for regime change in Iran, by force of arms if necessary.”

As for the big guy in the Oval Office, she suspects his clever plan is to rally his supporters around a “wartime” president as we head toward the 2020 elections. “We cannot just let it happen,” she declared.

May I offer a chill-pill? Over recent days, evidence suggesting that Iran’s theocrats were planning to strike American targets in the Middle East came to the attention of the U.S. intelligence community. In response, Mr. Trump deployed various defensive and offensive military assets to the region.

Through this show of force – as well as tweets – he is sending a message that a price will be paid should the Islamic Republic or its proxies do Americans harm. The technical term: deterrence. One way to measure power is to ask this simple question: Who deters whom?

Had the U.S. administration’s response been less robust, Iran’s rulers would have doubted American resolve – with good reason. For 40 years, they have been declaring their intent (“Death to America!”) while building their capabilities (e.g. their nuclear weapons program), confident that “America cannot do a damn thing.”

That was the pithy analysis of Ruhollah Khomeini, the Islamic Republic’s first supreme leader, after his followers occupied the American embassy in Tehran and went on to abuse the American diplomats they held prisoner for 444 days.

A few years later, agents of the theocratic regime bombed the U.S. embassy in Beirut killing 63 people and, not long after, the U.S. Marine barracks killing 241 US service personnel. President Reagan, focused on the Cold War, did not answer those attacks in any serious way.

Over the decades since, Iran’s rulers have hit Americans and others, many times, in many places, including assassinations of dissidents on European soil, and terrorist attacks on Jews in Argentina.

You may recall that in 2011, Iranians plotted to blow up the Café Milano in Georgetown while the Saudi ambassador was enjoying his dinner there. In response, President Obama did not a damn thing.

In 2016, American sailors in the Persian Gulf were seized and humiliated in flagrant violation of international law. Upon their release, Secretary John Kerry thanked Iran’s rulers.

Recently, the Pentagon calculated that roughly one in six American combat fatalities during the U.S. intervention in Iraq was attributable to the Islamic Republic. President Bush probably knew that, but decided against taking action – for example, destroying Iranian factories where IEDs (improvised explosive devices) and EFPs (explosively formed projectiles) were being manufactured.

Years spent courting elusive Iranian “moderates” culminated in the 2015 Joint Comprehensive Plan of Action which President Obama claimed prevents Tehran from acquiring nuclear weapons.

In truth, the deal – Ms. Sherman was lead negotiator under Mr. Kerry – communicated to Iran’s ruling mullahs: If you like your nuclear weapons program, you can keep your nuclear weapons program. You need only delay its visible progress for a few years. As for terrorism, the development of nuclear-capable missiles, the backing of mass-murderers in Syria, support for rebels in Yemen, and threats to your neighbors – we will cease to quibble over such trifles.

President Trump – advised by the notoriously hawkish and mustachioed Mr. Bolton, as well as Mike Pompeo, the preternaturally calm and clean-shaven Secretary of State – has been attempting to do more than repeat the mistakes of previous administrations.

His new and improved policies have included withdrawing from the toothless Iran deal, exerting serious pressure on the Islamic Republic’s economy, designating the Islamic Revolutionary Guard Corps as a terrorist entity (which it long has been) and, most recently, sending the Abraham Lincoln carrier group to the Persian Gulf.

On this last front, there are already signs that deterrence is having an impact: Iran has reportedly unloaded missiles from at least two dhows – small sailboats not immediately recognizable as military or threatening. In addition, two U.S. Navy destroyers have passed unhindered through the strategic Strait of Hormuz.

In fairness, let me conclude by saying that Ms. Sherman and other members of the aggrieved Iran-deal choir and its media echo chamber have been helpful – albeit inadvertently.

Had they reacted favorably or even just quietly to Mr. Trump’s muscle flexing, Supreme Leader Ali Khamenei might have dismissed the threat as one more bluff, and gone on to do worse than blow holes in four ships, none American, near the Strait of Hormuz. (That Tehran was behind these attacks is the “initial assessment” of the U.S. government.)

By contrast, the hysteria of those who oppose standing up to aggression has helped convince Iran’s theocrats that while President Trump may prefer the conflict not go kinetic, unlike his predecessors, he might – in response to their killing more Americans – decide that he can indeed do a damn thing.

Clifford D. May is founder and president of the Foundation for Defense of Democracies (FDD) and a columnist for the Washington Times.