After years of informal negotiations, the United States is facing mounting pressure to reach a civilian nuclear agreement with Saudi Arabia or risk getting shut out of the Gulf kingdom’s lucrative energy market.

But Riyadh’s refusal to give up on certain capabilities that could be used in a nuclear weapons program has caused concern among lawmakers that the Donald Trump administration may be too keen to strike a deal.

Under Section 123 of the US Atomic Energy Act of 1954, Congress must review any agreement to supply a foreign state with US nuclear technology. While the Trump administration has yet to publicly rule out any concessions, Saudi insistence on retaining the right to enrich uranium and to reprocess plutonium faces significant roadblocks on Capitol Hill.

“I think we have made clear — not that it was necessary — that a 123 agreement that in any way contemplated an enrichment program is going to face a lot of opposition in Congress,” a congressional source familiar with the debate told Al-Monitor. “So I just don’t think that the executive branch is going to go there.”