There are other, quieter ways to encourage peaceful outcomes in the Middle East. Congress — along with think tanks and private donors — should support conversations between scholars and opinion leaders in Iran, the United States, Europe and the Middle East. Such dialogue, sometimes joined by government representatives, can help de-escalate the potential for conflict. The recent Op-Ed essay in this newspaper by Hossein Mousavian, an Iranian scholar and former diplomat, and Abdulaziz Sager, a Saudi researcher, is one courageous first step in such a process .

Congress should also invite the foreign and defense ministers of France, Germany and Britain — all of which are signatories to the Iran nuclear deal — to testify about why it is in everyone’s interest to maintain the agreement and pursue diplomacy, not military action, in dealing with Iran. European security officials have already been contesting the characterization of American intelligence about Iranian threats. Hearing from such officials in Congress will, at the least, help Americans understand that the Trump administration is isolated from the rest of the world.

Europe has already done heroic work to keep the nuclear deal intact, but Paris, Berlin and London have a further role to play in helping Iran step away a potential conflict with the United States. Europe must make Instex, its financial mechanism designed to provide some investment and humanitarian assistance to Iran, real and viable. The Trump administration has threatened sanctions against Europe if Instex comes into force. With the possibility of a war that would be catastrophic for the entire world — including Europe — looming, that is a risk worth taking. American and European business leaders, members of Congress, and government and opinion leaders worldwide should publicly stand with European countries in this effort.

Finally, it is crucial that the news media in the United States and elsewhere continue its crusade for the facts about what is going on with Iran. We cannot repeat the days before the Iraq war when even many of our most reliable news outlets repeated and amplified what was, in fact, a flimsy case for war.

It’s quite possible that none of these actions will halt John Bolton, President Trump’s national security adviser, in his long-held ambition for regime change in Iran, by force of arms if necessary. And maybe even Mr. Trump sees promise in a “wag the dog” strategy in the run-up to the 2020 election, rallying his supporters around a “wartime” president. But a military conflict with Iran would have historic negative consequences for America’s national security, economy and standing in the world. We cannot just let it happen.

Wendy R. Sherman is a professor and the director of the Center for Public Leadership at the Harvard Kennedy School. She is the former under secretary of state for political affairs, lead negotiator of the Iran nuclear deal, and the author of “Not for the Faint of Heart: Lessons in Courage, Power and Persistence.”