The Hill | MARTIN B. MALIN:  President Trump’s decision to withdraw from the nuclear agreement with Iran will undermine U.S. power and influence around the world. Congress must closely monitor the reinstatement of sanctions on Iran to reduce the blowback on U.S economic interests, and provide strict oversight of the Trump administration’s evolving strategy toward Iran.

President Trump suggested that additional sanctions will force Iran to negotiate a better nuclear deal — one with permanent restrictions on Iran’s nuclear activities, “anytime, anywhere” access for inspectors (including to military sites), limits on ballistic missiles, and restraints on activities that challenge U.S. friends and allies in the Middle East. Mike Pompeo elaborated on US demands in his first major address as secretary of state.

But there is no reason to believe the president is correct. Though Iran may feel a pinch from the renewed sanctions — businesses are already canceling contracts for fear of running afoul of new U.S. sanctions — the pressure is unlikely to bring Tehran back to the negotiating table. The other parties to the Joint Comprehensive Plan of Action (JCPOA), including our closest European allies, are busy negotiating a continuation of the deal with Iran, including sanctions relief, absent the United States. Even by bludgeoningour allies with secondary sanctions, pressure on Iran is unlikely to produce the desired result.

Consider U.S. leverage. Oil revenues make up about 60 percent of Iran’s export earnings, with most of the oil going to just two customers, China and India. Neither country is persuaded by President Trump’s efforts to pressure Iran; either could step up purchases. It would take an extraordinarily zealous U.S. enforcement effort to make secondary sanctions on Chinese and Indian oil purchases bite. Moreover, market prices for oil and gas have been rising; Iran’s net losses in oil revenues may turn out to be negligible.

If the remaining parties to the JCPOA hold the agreement together, they will do so by effectively isolating the United States and working around U.S. sanctions, undermining U.S. influence globally. If, alternatively, U.S. sanctions succeed in depriving Iran of the benefits of the deal, Tehran will withdraw from the JCPOA, ramp up its nuclear program, and end the special monitoring that the nuclear deal puts in place — increasing the risk of proliferation or military conflict in the region. Whether or not the JCPOA collapses, sanctions will not force Iran to negotiate a “better deal” and the outcome will be unfavorable to U.S. national security.

Congress should prepare for each of these contingencies.

Congress should hold hearings to inform itself of the repercussions of U.S. secondary sanctions. European governments are livid at the prospect of the United States targeting their businesses and are looking for ways to retaliate. The European Union could take action against the United States through the World Trade Organization (WTO), apply tariffs on U.S. imports to Europe, or impose counter-sanctions against U.S. banks and companies. The European Union already has begun efforts to indemnify European companies from losses because of U.S. sanctions enforcement. The American people should understand the costs and consequences of U.S. sanctions enforcement.

Congress can help to minimize the backlash from our allies and partners by requiring the executive branch, prior to the application of secondary sanctions, to provide an assessment of risks and benefits and to certify that each proposed measure advances the economic and national security interests of the United States.

Finally, if the nuclear deal collapses and Iran resumes the unconstrained enrichment and stockpiling of uranium and other activities of concern, while scaling back access for international inspectors, a military crisis is almost certain to follow. John Bolton has consistently argued in favor of bombing Iranian nuclear facilities. Congress must be prepared to assert its constitutional authority and to restrain the Trump administration from leading the United States into another devastating war in the Middle East.

It is not hard to imagine how the lead up to war would unfold or what some of the consequences will be. Prime Minister Benjamin Netanyahu’s 55,000 pages of documents allegedly containing new information about past nuclear weapons development in Iran will be waived before the public. U.S. officials and nonproliferation experts will demand proof that all nuclear weapons activities in Iran have really ceased. Iran will, of course, play the defiant victim and refuse to allow any further investigation of the possible military dimensions of its nuclear program.

U.S. military strikes on Iran, possibly coordinated with Israel and Saudi Arabia, will be justified as the last resort to prevent Iran as “the leading state sponsor of terrorism” from acquiring nuclear weapons.

Iran’s means of responding to an attack on its nuclear facilities will be limited but also protracted. With the Middle East smoldering with tension, the violence will not be confined to Iranian territory. The United States will be drawn deeper into a collapsing black hole of region-wide conflict. The costs in blood and treasure could be substantial.

But that will not be the only consequence. An attack on Iran may finally convince Iranian leaders to pursue nuclear weapons in earnest. In February 2018, the U.S. intelligence community assessed Iran had yet to make such a decision. But if Iran decides to acquire the bomb, it will draw on close to two decades of experience not only with how to produce the materials and components it needs, but also how to hide and protect a covert program. Using force against Iran will not prevent its emergence as a nuclear-armed state. It may hasten that outcome.

Given the risks and dangers of even a limited attack on Iran’s nuclear facilities, if the JCPOA collapses as a result of President Trump’s May 8 decision, Congress should move expeditiously to prohibit the use of force against Iran without explicit congressional authorization.

President Trump’s withdrawal from the Iran nuclear deal was a major foreign policy blunder. Congress must act to minimize the damage.

Martin B. Malin is executive director of the Project on Managing the Atom at the Belfer Center for Science and International Affairs in the John F. Kennedy School of Government at Harvard University. His research focuses on arms control and nonproliferation in the Middle East, U.S. nonproliferation and counterproliferation strategies, and the security consequences of the growth and spread of nuclear energy.