President Donald Trump was clearly surprised Monday — and asked "why?" — when Treasury Secretary Steven Mnuchin said U.S. officials asked members of China's trade delegation to cancel a scheduled farm tour in the United States last week.

American stock market indices plunged Friday on the news of the cancellation of the visit with farmers in Bozeman, Montana, and Omaha, Nebraska, after the Chinese delegation concluded trade talks in Washington.

Trump was asked Monday how the cancellation could affect trade talks with China. The question came during a bilateral meeting at the United Nations between Trump, other administration officials, and Egyptian President Abdel Fattah el-Sissi.

"Well, they're starting to buy a lot of our ag product," Trump said. "But Steven, could you maybe," the president said, referring to Mnuchin.

Mnuchin then said, "That was actually at our request they delayed that."

"So, we didn't want there to be any confusion. They have started buying agriculture," the Treasury chief continued. "They're going to reschedule that at a different time. The timing didn't work. But that was — that was purely at our request."

Trump then asked Mnuchin, "Why was that our request, just out of curiosity?"

The president punctuated that question with a chuckle that seemed to indicate displeasure — or unease — more than humor.

Mnuchin started to answer, "We didn't want confusion around the trade issues."

Trump quickly interjected, "Yeah, but I want them to buy farm products."

Mnuchin then responded, "There was no confusion, we want them to buy agriculture. They've committed to buy agriculture. And they're doing that."

Trump added, "They've committed to buy a lot of agriculture, and they're going to start, and they've started."

"And we should get them over there as soon as possible so they can start buying," the president said.

Trump has a history of contradicting Mnuchin in public about various issues, including on alleged currency manipulation by China, linking security concerns about the technology company Huawei with trade talks with China, and on setting conditions for negotiations with Iran.