“The possibility that U.S.-manufactured aircraft could be used as tools of terror is absolutely unacceptable and should not be condoned by the U.S. government,” Rubio and Roskam wrote. “The United States should revoke authorizations and re-impose sanctions on Iranian airlines found guilty of such support, and should bar U.S. companies from selling aircraft to Iran until the Iranian regime ceases using commercial airliners for illicit military purposes.”

The Obama administration granted a license authorizing Boeing to strike the deals last fall, following Iranian complaints that they were not receiving the expected economic benefit of the sanctions relief provided by the nuclear pact. “We are going to do what we can to meet our commitments as long as Iran continues to meet their nuclear-related commitments,” then-State Department spokesman John Kirby said.

The Obama administration did far too much to help Iran, Republican lawmakers maintained, and they responded with legislation that would bar U.S. banks from financing the deal. “Why should U.S. banks and their customers be implicated in Iranian atrocities?” Rep. Bill Huizenga, R-Mich., said in November.

Democrats countered that attempts to undermine the Boeing sales would ‘unravel’ the nuclear agreement. “I’m going to bet that under the Trump administration, Republicans will not be so eager to move legislation to unravel this agreement because, like the rest of us, they do not know how Mr. Trump will govern and because they know there is no other reasonable approach to curbing Iran’s nuclear ambition short of military intervention,” Rep. Maxine Waters, D-Calif., said at the time.

Trump has sent mixed messages on the Iran deal, by turns denouncing it and complaining that Iran wouldn’t spend the money received through the nuclear deal with U.S. companies. “I think it is an imperfect arms control agreement,” Defense Secretary Jim Mattis said during his confirmation hearings in January. “When America gives her word, we have to live up to it and work with our allies.”

Roskam and Rubio should have at least one ally in the Trump adminstration, in the former of current CIA director Mike Pompeo. “It is not your role to act as agents of the Iranian Chamber of Commerce,” then-Congressman Pompeo wrote to the Obama administration in protest of the airplane sales last year. “America’s security depends on you acknowledging that this agreement has not changed Iran’s behavior in any material way.”

Trump’s decision to attack Syrian President Bashar Assad, who is being supported in his ongoing civil war by Russia and Iran, might give Iran hawks such as Rubio and Roskam a chance to press their case. “As the main benefactor of Bashar al-Assad—whose regime has once again used chemical weapons to kill scores of men, women and children—Iran has consistently used commercial aircraft to transport the weapons and troops that have fueled the conflict in Syria which has claimed the lives of nearly 500,000 people,” they observed in Monday’s letter. “We therefore strongly urge you to prohibit U.S. companies from selling aircraft to Iran until Iran stops using commercial aircraft to advance its terror campaign around the world.”