Michael Pillsbury, a China scholar at the Hudson Institute who sometimes advises Trump, said the president’s move on Friday reflected the fact he had grown increasingly frustrated with China’s response to his escalating tariffs in recent months.

“The president has been increasingly frustrated in the last three months’’ with China after the May breakdown of talks that he believed were about to yield a deal, said Michael Pillsbury, a China expert with the Hudson Institute in Washington with whom Trump has consulted in the past.