Iran is the leading state sponsor of terrorism. The mullah regime is providing weapons to kill our soldiers in Iraq. It is working furiously to develop nuclear weapons. We certainly do not want to go to war against Iran — though perhaps we could do a more aggressive job of keeping the mullahs’ minions out of Iraq. But we have other weapons that are being deployed now — not by the military, the federal government, or officials in Washington, but by state government officials and legislatures in state capitals, who are working to divest their pension funds of stocks in companies that do business in Iran.

The divestment movement has been gaining speed during the past year. In 2006, the Missouri state treasurer, Sarah Steelman, ordered the Missouri Investment Trust to divest stock in companies that do business in Iran.

The California Assembly has passed a divestment bill, and it is now before the state Senate; Governor Schwarzenegger has promised a major signing ceremony if it passes.

A bill limited to Iran’s energy sector has been passed into law in Florida. A divestment bill has been passed in committee in the Pennsylvania House, and a divestment resolution was passed by the Georgia Senate. In Louisiana, a bill to set up a “terror-free international index” has been passed into law. Divestment bills have been filed in Ohio, New Jersey, Michigan, New York, Massachusetts, Maryland, and Texas.

Many of these bills have met with opposition. Pension fund administrators, such as those at California’s giant CalPERS, have opposed them. They argue that divesting would cost them money.

But the fact is that American-based companies already are prohibited from doing business in Iran. Firms that do the most business in Iran are French — Alcatel, BNP Paribas, Total; Italian — ENI; Korean — Hyundai; Chinese — PetroChina; and Russian — Statoil. The potential losses to pension funds are almost certainly minimal; a fund can find plenty of international stocks for its portfolio without touching those who do business in Iran.

At the same time, divestment can hurt the targeted companies enough to persuade them to change their ways. We learned this 20 years ago from the divestment movement directed against apartheid South Africa, which targeted many American-based firms. Some of them withdrew from South Africa — a fact that helped persuade South Africa’s white rulers to end apartheid.

We can’t expect the mullahs to change their system in the same way. But we can expect divestment to put a heavy economic squeeze on a regime whose economy already is deteriorating visibly.

Iran produces lots of oil, but it doesn’t have enough refinery capacity and must import gasoline. The mullah regime appears to be highly unpopular, and further economic deterioration might spark a peaceful overthrow — the best result imaginable for us, as well as for most Iranians.

What of private pension funds? Here the lead is being taken by the president of Teamsters Union, James Hoffa, who last week urged managers of 170 funds that invest Teamster pension money to sell all shares of companies that do business in Iran.

Mr. Hoffa has vigorously protested the arrest and torture of union leaders in Iran and seems to be following in the steps of the late president of AFL-CIO, Lane Kirkland, who did so much to destabilize communism in Eastern Europe. Divestment by private pension funds will be aided if the Senate passes the bill — sponsored by Representatives Frank and Kirk, Senators Obama and Brownback, and already passed by the House — to shield investment managers from lawsuits based on any losses from terror-free investing.

In a time of great partisan strife, the divestment movement is deeply bipartisan. Bills have been passed in the heavily Democratic legislature in California and the heavily Republican legislature in Florida.

Sponsors include supporters of the war in Iraq — including Ohio legislator Josh Mandel, now on his second deployment there as a Marine reservist — and strong opponents. We may not be at war with the mullah regime, but they have been waging war against us for a long time, since the hostage seizure in 1979 and the bombing of the Marine Corps barracks in Lebanon in 1983.

You sometimes hear the criticism that ordinary Americans have not been asked to make any sacrifices or take any action in our war against terrorists. But as Ms. Steelman, dozens of state legislators and the Teamsters’ Mr. Hoffa have shown, there is something we can do. Stopping the flow of investment funds into companies that, opportunistically, do business with the number one terrorist-supporting regime in the world doesn’t guarantee success. But it’s a step in the right direction.