(Bloomberg) -- The Trump administration is considering blocking planned sales by Boeing Co., Airbus SE and General Electric Co. to Iran, as the president reconsiders the 2015 deal to curb the Islamic Republic’s nuclear program, a person familiar with the matter said.

No recommendation has yet been made to President Donald Trump and his administration is also considering letting the sales proceed, the person said.

Blocking the sales would potentially lead Iran to abandon the nuclear deal, an alarming prospect for some of Trump’s national security advisers. The decision also puts in conflict two of Trump’s top priorities: confronting Iran, and reinvigorating American manufacturing.

Boeing, the top U.S. exporter, has about $20 billion in jetliner sales to Iran planned. If completed, the transactions would be the first U.S. aircraft exports to Iran since the Shah era in the 1970s.

Trump has long had the Iran nuclear deal, signed by his predecessor, Barack Obama, in his sights. The president announced in October that the agreement didn’t serve U.S. national security interests and that Iran wasn’t living up to the spirit of the accord, citing its involvement in military conflicts in Syria and Yemen. He refused to certify that Iran was in compliance with the agreement, a move that allows Congress to re-impose sanctions on the country that were relaxed after Obama signed the deal.

But Congress hasn’t acted on its authority and the U.S. hasn’t withdrawn from the deal it signed with Iran, Germany, the U.K., Russia, China and the EU.

The Wall Street Journal reported earlier on Friday that the Trump administration was considering blocking the sales, partly out of concern that Iran would use the planes to transport military equipment to its allies in Syria and elsewhere.

A State Department official, who asked not to be identified discussing internal deliberations, said the administration would not issue export licenses for sales to Iran unless they are convinced the aircraft will only be used for civilian passenger aviation.

Boeing and Airbus already have export licenses from the Treasury and Commerce Departments allowing them to sell plans to Iran Air, the country’s national carrier. The first Boeing deliveries are scheduled for late 2018. Boeing continues to discuss the sales with the Trump administration and has said it won’t go forward with the deal if it’s in conflict with U.S. foreign policy.

“We continue to follow the lead of the U.S. government on all issues related to Iran,” Boeing spokesman Chaz Bickers said on Friday.