President Trump doesn't plan to interfere with European investment in Iran, according to Secretary of State Rex Tillerson.

"The president's been pretty clear that it's not his intent to interfere with business deals that the Europeans may have under way with Iran," Tillerson told the Wall Street Journal. "He's said it clearly: ‘That's fine. You guys do what you want to do.'"

That commitment could be a key factor in the maintenance of the Iran nuclear deal, known as the Joint Comprehensive Plan of Action, contrary to Trump's stated policy preferences. The president called for a series of new restrictions on the regime's aggression, in a denunciation of the pact that flew in the face of European preferences. But Trump is apparently stopping short of threatening to impose sanctions that curtail potential investments.

If he maintains that position, Iran could continue to receive most of the benefits provided by the JCPOA. Former President Obama waived sanctions on Iran in exchange for compliance with the nuclear restrictions specified in the deal, but the lion's share of investment Iran since that time has come from Europe rather than the United States.

"For us, it is a matter of security, it is a matter of keeping channels of engagement, dialogue and cooperation with Iran opened; from the economic cooperation to the cooperation we have in other sectors — following the [deal's] implementation," Federica Mogherini, the European Union's top foreign policy official, told reporters Monday.

Trump's congressional allies hope that the president's refusal to certify the Iran deal will induce both European allies and the regime to negotiate new restrictions on the nuclear and ballistic missile programs. Sen. Tom Cotton, R-Ark., one of the leading proponents of Trump's new Iran strategy, is writing a bill that would mandate the renewal of economic sanctions on Iran if the regime develops the capability to build a nuclear bomb within less than a year.

"Our allies in Europe and Asia at that point can decide whether they would like to do business with the largest economy in the world ... or a terror-sponsoring country's economy that's approximately the size of the Maryland's economy," Cotton told the Washington Examiner in September. "I think that's a pretty easy choice for foreign leaders."

Trump's rhetoric when he outlined that new strategy at the White House seemed consistent with Cotton's tactics. "In the event we are not able to reach a solution working with Congress and our allies, then the agreement will be terminated," Trump said. "It is under continuous review and our participation can be canceled by me at any time."

Tillerson sounded a less-threatening note. "We've been working with the Europeans for six months," he said in the Thursday interview. "They have been brought along with this same thought process. It doesn't mean that they necessarily agree entirely with it… Now we will start a more formalized process with them now that the policy's been adopted."