Officials maintained they thought about it long and hard. Sanctioning the leader of another country was rarely done, and never with the leader of a national security partner. Although the crown prince does not have a U.S. visa, and U.S. officials indicated he would not be getting one any time soon, any such decision would be infinitely more problematic once he became king, which he is virtually certain to be with the passing of his 85-year-old father.

And the crown prince was unique. Banning the grandson of the founder of Saudi Arabia would mean declaring what a senior administration official called a “hostile” relationship with the kingdom, the titular protector of the holiest sites in the Muslim world.

Even if that were tolerable, in a dangerous region where the United States seeks Saudi leadership and cooperation, untangling Mohammed’s assets for freezing from those of the kingdom was seen as virtually impossible.

“Having looked at this extremely closely, over the last five weeks or so, really, the unanimous conclusion [was] that there’s just more effective means to dealing with these issues going forward,” said a senior official, speaking on the condition of anonymity to explain the behind-the-scenes reasoning.