Huffington Post is reporting that U.S. Sen. Tom Cotton injected a note of acrimony into a chummy private meeting between billionaires and Republican lawmakers by sharply challenging Apple CEO Tim Cook over the company’s refusal to help the FBI get into iPhones.

Tom Cotton unpleasant? 

The exchange, which took place at the American Enterprise Institute’s World Forum, left a number of attendees “a little uncomfortable about how hostile Cotton was,” a source familiar with the back-and-forth told The Huffington Post on Monday.

A senator who was present for the argument told HuffPost that there was some discussion of whether Apple had “done some things for China that they weren’t willing to do for the U.S.”

The senator described the Cotton-Cook exchange as “tense.”

“I don’t think he’s used to being spoken to in such an adversarial manner,” added the senator, referring to Cook. “I don’t think he gets that from his subordinates.”

Also under discussion were ways to stop Donald Trump from getting the Republican presidential nomination. No word in Huffington Post that Cotton revealed his preference in the race besides the obvious — himself.