IP3 officials sent documents to Mr. Flynn for Mr. Trump to approve, before and after the inauguration, despite warnings by career and political staff members that the White House was ignoring laws requiring the president to keep lawmakers abreast of negotiations on nuclear cooperation agreements and submit the agreements to Congress for review and approval, according to the report.

Early in 2017, legal adviser s for the National Security Council agreed that Mr. Flynn had a potential conflict of interest. But despite at least two warnings — by the legal advisers and by H.R. McMaster, Mr. Flynn’s successor as national security adviser — that the N.S.C. staff stop work on the plan, the White House has continued to pursue it with Mr. Barrack as the designated point man. Mr. Trump reportedly met with nuclear power developers as recently as Feb. 12.

The United States has long been a leader in nuclear technology, the sale of which is governed by bilateral pacts, called “123 agreements,” which require adherence to nine nonproliferation criteria. Some 21 countries, the European Union and the International Atomic Energy Agency have these agreements.

The criteria include guarantees that none of the nuclear materials provided by the United States will be used for explosives, that none of the technology or classified data will be transferred to third parties without American consent, and that the other country involved in the agreement will not enrich uranium or reprocess plutonium, which could be a pathway to a nuclear bomb.

The requirements are intended to prevent another country from gaining nuclear weapons. The Saudis say they want the technology only to produce nuclear power for domestic purposes and thus prolong their oil reserves, not to acquire a weapons capability.

But it’s hard to trust such assurances, given Saudi animosity toward Iran and Prince Mohammed’s 2018 comment, “Without a doubt, if Iran developed a nuclear bomb, we will follow suit as soon as possible.”

Although Iran never produced a nuclear weapon, it had a robust nuclear program until it agreed to an international deal in 2015 that curbed its activities. The deal, opposed by the Saudis, is now hanging by a thread because Mr. Trump abrogated America’s commitment.