By DIETHARD PALLASCHKE | FROM TODAY’S WALL STREET JOURNAL EUROPE

At the U.N. General Assembly last month, German Foreign Minister Frank-Walter Steinmeier condemned a speech by Iranian President Mahmoud Ahmadinejad as “blatant anti-Semitism.” Mr. Steinmeier also criticized Iran’s “delaying tactics” on the nuclear issue and warned that the Iranian government “must not exhaust the patience of the international community.” But was he really challenging Iran’s nuclear-weapons program?

For all his tough words, Mr. Steinmeier never said what steps the international community should take if Iran continues its “delaying tactics.” His British and French colleagues recently repeated their willingness to impose unilateral European sanctions on Iran if Russia and China block new sanctions resolutions in the Security Council. However, Mr. Steinmeier opposes European sanctions, saying they exceed the U.N. mandate. Indeed, so far there is little sign of the Germany government implementing any measures to thwart Iran’s ambition to develop nuclear weapons.

Yet no country has more powerful leverage. Germany in particular can exert highly effective economic pressure on Iran. German political scientist Matthias Küntzel has estimated that two-thirds of all Iranian companies use German technology. Simply depriving Iran of German spare parts would severely disrupt Iran’s industry.

More than 1,700 German companies are active in Iran. These include household names like Linde, ThyssenKrupp and BASF. Germany’s technology and telecommunications giant Siemens has made the biggest financial commitment. As part of a continuing $450 million deal started in 2006, Siemens is committed to sell Iran 150 locomotive engines over six years and to transfer the technical know-how for manufacturing them in Iran within 10 years.

Clearly, Germany by itself has enough economic leverage with Iran to persuade its leaders to halt uranium enrichment, as demanded by the U.N. And yet there is no sign of a will to use it. In fact, German-Iranian business ties are flourishing more than ever. Germany is still Iran’s most important trading partner in the West. After a two-year decline, German exports to Iran grew in the first quarter of 2008 by 13.6%, as compared to the same period in 2007. The German control office for foreign trade (BAFA) approved 1,926 business deals from January through July 2008, an astonishing increase of 63% over the same period last year.

In February of this year, BAFA also issued “zero notices” to the German engineering company Steiner-Prematechnik-Gastec (SPG) for the construction of three gas-liquefaction plants in Iran. The zero notices — permits, in effect — state that the construction of the plants does not violate international sanctions.

The Steiner gas deal came to light when British Prime Minister Gordon Brown suggested implementing tougher sanctions against Iran, especially in the sector of liquefied gas. The gas deal’s obvious flouting of international efforts led to national and international protests. Several German politicians criticized it, specifically pointing to the involvement of Hartmut Schauerte, a member of the German cabinet, who, according to company owner Bernd Steiner, lobbied for the deal. Mr. Schauerte denied that he had tried to influence the decision. When the Israeli Foreign Ministry complained about the bargain, German Chancellor Angela Merkel felt obligated to comment, saying that “German firms should show more sensitivity in their dealings with Iran.”

The chancellor’s comment points at the heart of the problem, which is the government’s unwillingness to enact a national law that would inhibit a deal with Iran in the energy sector. Instead, it counts on “voluntary self-restraint” of the companies.

Furthermore, the most important German political think tank, the “Stiftung Wissenschaft und Politik” (SWP), is pushing in the opposite direction by calling for reducing sanctions and intensifying bilateral talks with Iran. Volker Perthes, director of the SWP (and an adviser to Foreign Minister Steinmeier) has been calling for a “strategic partnership” with Iran since 2006. In his new book, “Iran: A Political Challenge,” he advocates confidence-building measures and the development of an energy partnership between Iran and the EU. He also pleads for collaboration in all areas. According to Mr. Perthes, “This [strategic partnership] would especially include energy partnership, collaboration in development matters, science and technology, as well as in certain aspects of internal and regional security issues.”

Mr. Perthes also states that the policy of carrots and sticks toward Iran has failed, and he favors strengthening the carrots and discarding the sticks. In his book, he argues that this strategy will succeed because the Iranian regime is acting rationally: For Mr. Perthes, the religious ideology of the mullahs is irrelevant when it comes to foreign policy. In this realm, only national interest would guide the regime’s behavior, so that accepting Iran’s view of its security needs and offering far-reaching concessions would smooth the conflict.

Hopefully, Foreign Minister Steinmeier looks at Tehran through a different lens. But is he ready to back up his commendable and tough-sounding U.N. speech with equally tough foreign-policy and economic actions that demonstrate Germany’s commitment to halting Iran’s nuclear-weapons program? Germany has the economic power to make Iran’s leaders reconsider their determination to pursue this program. Verbal reprobation of the Iranian regime is not enough. It must be followed by determined action before it is too late.

Mr. Pallaschke is a mathematician and the chair of “Operations Research” at the University of Karlsruhe, Germany. He is also the chairman of the German chapter of the Scholars for Peace in the Middle East.