Mitt Romney, a former governor of Massachusetts, is a Republican candidate for president.

Beginning Nov. 4, 1979 , dozens of U.S. diplomats were held hostage by Iranian Islamic revolutionaries for 444 days while America’s feckless president, Jimmy Carter, fretted in the White House. Running for the presidency against Carter the next year, Ronald Reagan made it crystal clear that the Iranians would pay a very stiff price for continuing their criminal behavior. On Jan. 20, 1981, in the hour that Reagan was sworn into office, Iran released the hostages. The Iranians well understood that Reagan was serious about turning words into action in a way that Jimmy Carter never was.

America and the world face a strikingly similar situation today; only even more is at stake. The same Islamic fanatics who took our diplomats hostage are racing to build a nuclear bomb. Barack Obama, America’s most feckless president since Carter, has declared such an outcome unacceptable, but his rhetoric has not been matched by an effective policy. While Obama frets in the White House, the Iranians are making rapid progress toward obtaining the most destructive weapons in the history of the world.

The gravity of this development cannot be overstated. For three decades now, the ayatollahs running Iran have sponsored terrorism around the world. If we’ve learned anything from Sept. 11, 2001, it is that terrorism in the nuclear age holds nightmarish possibilities for horror on a mass scale.

What’s more, Iran’s leaders openly call for the annihilation of the state of Israel. Should they acquire the means to carry out this inhuman objective, the Middle East will become a nuclear tinderbox overnight. The perils for Israel, for our other allies and for our own forces in the region will become unthinkable.

The United States cannot afford to let Iran acquire nuclear weapons. Yet under Barack Obama, that is the course we are on.

As president, I would move America in a different direction.

The overall rubric of my foreign policy will be the same as Ronald Reagan’s: namely, “peace through strength.” Like Reagan, I have put forward a comprehensive plan to rebuild American might and equip our soldiers with the weapons they need to prevail in any conflict. By increasing our annual naval shipbuilding rate from nine to 15, I intend to restore our position so that our Navy is an unchallengeable power on the high seas. Just as Reagan sought to defend the United States from Soviet weapons with his Strategic Defense Initiative, I will press forward with ballistic missile defense systems to ensure that Iranian and North Korean missiles cannot threaten us or our allies.

As for Iran in particular, I will take every measure necessary to check the evil regime of the ayatollahs. Until Iran ceases its nuclear-bomb program, I will press for ever-tightening sanctions, acting with other countries if we can but alone if we must. I will speak out on behalf of the cause of democracy in Iran and support Iranian dissidents who are fighting for their freedom. I will make clear that America’s commitment to Israel’s security and survival is absolute. I will demonstrate our commitment to the world by making Jerusalem the destination of my first foreign trip.

Most important, I will buttress my diplomacy with a military option that will persuade the ayatollahs to abandon their nuclear ambitions. Only when they understand that at the end of that road lies not nuclear weapons but ruin will there be a real chance for a peaceful resolution.

My plan includes restoring the regular presence of aircraft carrier groups in the Eastern Mediterranean and the Persian Gulf region simultaneously. It also includes increasing military assistance to Israel and improved coordination with all of our allies in the area.

We can’t afford to wait much longer, and we certainly can’t afford to wait through four more years of an Obama administration. By then it will be far too late. If the Iranians are permitted to get the bomb, the consequences will be as uncontrollable as they are horrendous. My foreign policy plan to avert this catastrophe is plain: Either the ayatollahs will get the message, or they will learn some very painful lessons about the meaning of American resolve.