In its 32 years, the Islamic Republic of Iran has killed lots of U.S. Marines.  The Iranians were behind the 1983 Beirut barracks bombing, which killed hundreds of Marines. They were behind the bulk of deadly IEDs in Iraq and Afghanistan, which killed and maimed hundreds more. Iran has been killing Americans all over the world for decades. And now the Tehran regime is set to kill another: Amir Mirzaei Hekmati, a 28-year-old American, Arizona-born, Michigan-raised — and former Marine. Hekmati was visiting family in Iran last summer when he was apprehended by authorities. This week, the regime has decided to give him the death sentence.

Hekmati reportedly worked for a New York-based video game company, which had a “hearts and minds” contract with the CIA. And so the mullahs accuse him of being a CIA spy. The extent of Hekmati’s espionage — whether nonexistent or knee-deep — shouldn’t matter. The man is a captured American citizen set to be murdered by a sworn enemy.

We are at a breaking point in 2012. Iran, this national security issue of such magnitude, will reach a crescendo during this year’s presidential election. President Obama and the Republican candidate will spend the better part of the year debating how to handle Iranian hostility with prudence. The wisest course is narrowing down to the only course: regime change in Tehran.

This does not mean military action — nor does it mean invasion, conquest, or occupation. Regime change, in the case of Iran, means open support for a “Persian Spring.” It means replicating the Reagan-Thatcher model vis-à-vis Lech Walesa in Poland and the late Vaclav Havel in Czechoslovakia: supporting Iranian dissident and opposition groups rhetorically, politically, financially, materially, and morally until a popular uprising — simmering in Iran since the Green Movement in 2009 — brings down the few hundred or so theocratic mullahs threatening the world.

We must do this for many reasons, but four big ones come to mind.

1. To avoid a war.

If the Iranian regime is not replaced, it will lead to war. The Israelis may preemptively attack Iran’s nuclear facilities. If the Israelis do not take action, the United States might do so. And if neither Israel nor the U.S. takes action, the Iranians themselves will continue to be the aggressors geopolitically.

Bringing down the mullahs internally would turn our most hostile enemy into a natural ally. It is unclear what type of Iranian government would emerge following the downfall of the mullahs. But one thing is clear: unlike Egypt and Libya and other Arab uprisings where the Muslim Brotherhood might take over for good, the Iranian people are far friendlier to the United States. Iran’s 70 million people are amongst the youngest in the world. They want to be connected to the rest of the planet. They want the freedom to worship — or not worship — as they please. They want to use the Internet free from censure; to assemble free from threat; to read, write, and speak free from intimidation. They do not want war with the West. They do not want to fight and die to restore the twelfth century or to bring back the Twelfth Imam.

2. To avoid nuclear blackmail, nuclear proliferation, and nuclear terrorism.

Should nothing be done — should the mullahs obtain a nuclear weapon in 2012 — the world will enter, as Churchill once phrased it, “the abyss of a new Dark Age, made more sinister, and perhaps more protracted, by the lights of perverted science.” Never before have such apocalyptic, self-destructive, suicidal religious psychopaths had such cataclysmic technology. The plausibility of nuclear terrorism does not need to be discussed here: Either one soberly comprehends this threat or one does not. Many do not understand this threat and its long-term implications.

But the issue need not be a mushroom cloud over Manhattan. Imagine the Iranian supreme leader making demands of the world, with the implicit threat of a nuclear suitcase-armed Hezbollah or al-Qaeda operative in Washington, D.C., London, Paris, or Tel Aviv ready to “blow” should these demands not be met. This is the world of 2013 and 2014 should Iran be allowed to go nuclear: the whole world would be held hostage to the nuclear blackmail of the mad mullahs.

In addition, the Saudis, the Egyptians, the Turks, and maybe even the Jordanians would all pursue nuclear weapons to deter Iranian belligerence. (Not to mention the Israeli, Pakistani, and Indian nuclear arsenals.) We would have a wide-ranging Middle East nuclear arms race. Nobody should think such a development would end well.