During his recent visit to the United Nations, Iranian president Mahmoud Ahmadinejad accused the United States government of orchestrating the September 11 terrorist attacks.

Most of us weren’t surprised. After all, he has previously called 9/11 a “big lie” and for Israel to be “wiped off the map.”

We were surprised, though, that the theocrat dictator from Tehran was welcomed Hilton Manhattan East Hotel. Most hotels in New York City refused to host him.

When Ahmadinejad attended the UN’s fall 2009 conclave, the Essex House on Central Park South, the New York Helmsley, and the Omni Berkshire Hotel all refused to turn down the sheets for Ahmadinejad and the other thugs in his traveling party.

Officials of a government that greets peaceful, pro-democracy demonstrators with rifle fire do not deserve even one good night’s sleep on American soil.

Companies that have rebuffed this brutal regime go far beyond the hospitality industry and far away from New York City. Caterpillar, General Electric, Ingersoll Rand, KPMG and Toyota are just a few of the major corporations that have stopped doing business in Iran. Because the regime’s cronies pervade Iran’s society and economy, these businesses realize that their presence in Iran lends legitimacy to the regime. And doing business in Iran can lead, wittingly or otherwise, to material support for a government that is developing an illegal nuclear weapon in the face of international condemnation and that is a brutal violator of human rights.

This is the same regime that stones women to death. While activist across America are promoting gay marriage, President Ahmadinejad denies that there are homosexuals in Iran and those that are discovered are hanged.

Most important, refraining from business in Iran lowers the odds that Tehran’s mullahs will acquire the ultimate billy club — a nuclear weapon — that it would wield in the already volatile Middle East. The Iranian regime sponsors Hamas and Hezbollah, supplying them with rockets fired into Israel’s residential neighborhoods and test-fires its own long-range ballistic missiles for potential attacks on the Jewish State. A nuclear weapon will only empower Iran to further bully other more moderate Arab states in the region and is a clear threat to U.S. troops in Afghanistan, Iraq and the rest of the Persian Gulf.

Lest Iran enjoy nukes all to itself, Egypt, Saudi Arabia, Turkey, and perhaps others in that troubled neighborhood would become keenly interested in acquiring their own nuclear weapons, to deter Iran.

The sanctions that Congress and President Obama imposed on Iran on July 1 are helping frustrate the mullahs’ nuclear ambitions. Among other provisions, the sanctions preclude companies that conduct business in Iran from doing business with the U.S. government.

Honeywell, for instance, helps develop critical oil refineries in Iran – and has also earned some $12.9 billion in contracts from the U.S. government over the last decade. It soon must decide if it prefers to make money in Tehran or Washington, D.C.

With the growing tide of outrage against companies operating in Iran, companies like Honeywell and its highly paid CEO, David Cote, must decide if short term profits from doing business in Iran outweigh their growing status as business pariahs who may no longer be welcome to do business in Iran.Dozens of foreign corporations will be making the same choice, including Finnish communications company Nokia, Danish shipping giant Maersk, Japanese construction conglomerate Komatsu and Russia’s leading oil producer, Lukoil.

Denying the Iranian government nuclear weapons and prodding it to improve human rights will demand the dedication of American diplomats, democracy activists, and intelligence officers. It also will require the moral clarity and savvy long term business views of business men and women willing to forego profits from everything from Iranian-government hotel guests, to lucrative contracts in the Iranian petroleum industry. Now is the time for “private sanctions” where all businesses come together to stop doing business in Iran — a small price to pay to prevent Iran from getting the bomb.