Iranian President Mahmoud Ahmadinejad generally shrugs off American sanctions against Iran. "Americans are not able to harm us," he said last October.

Ahmadinejad may come to eat his words. On Tuesday, a bipartisan agreement was struck in the U.S. Senate to expand economic pressures in Iran. Under the plan, states and local governments would be authorized to divest from companies that do business with Iran's oil and gas sector and cut off shipment through other countries of sanctioned technology.

The agreement, to be taken up by the Senate Banking Committee on Thursday, represents growing impatience with Iran, which Sens. Christopher J. Dodd, D-Conn., chairman of the Senate Banking Committee and Richard Shelby, R-Ala., the panel's senior Republican, call a threat to U.S. interests and allies.

Because the United States has not had a diplomatic presence in Iran since the hostage crisis of the late 1970s, it can be difficult to interpret Iran's actions and political maneuvering. However, Iran did not endear itself to the United States or its allies with its recent tests of long-range missiles. Defense experts say the tests suggest Iran seeks an improved capacity to strike at U.S. interests and at Israel. However, American officials do not believe that Iran has mastered enriching uranium to build nuclear weapons. Nor do the recent military tests suggest its defense capabilities have vastly improved. More trade and economic sanctions are needed to ensure it is stymied on both fronts.

Meanwhile, the United States is committed to a full array of diplomatic tools in its relations with Iran. Iran has been offered civilian nuclear fuel, agriculture assistance and peaceful exchanges of students if it suspends its enrichment activities. Force remains an option but only as a last resort, U.S. officials have said.

For now, broad-based sanctions are a sensible tool to deal with a leader who on the one hand says he would welcome bilateral relations with the United States yet conducts missile tests intended to threaten Israel and U.S. interests.

Dodd and Shelby are on the right track. The Senate Banking Committee and the full Congress need to take the next steps.