The tweet on corporations being “ordered” to leave, aides said, was drafted, however imprecisely, with a method in mind, sending a notice to corporations to leave China on their own.
Supporters of a muscular approach said Mr. Trump was waging a smart and necessary pressure campaign against China, which has unfairly taken advantage of the United States for decades while other presidents failed to take strong enough action.
If it ultimately results in jobs and factories returning to the United States, they argue, it will benefit both the country and the president’s political standing.
“Since the beginning, Trump has been the source of stability in this relationship,” said Stephen K. Bannon, Mr. Trump’s former chief strategist. “Today, China showed they are engaged in economic war against the United States. The president fired a warning shot to corporate America — this war will not end quickly; it’s time to bring your supply chains home.”
The president’s comments come at a time when Mr. Trump, known for a visceral brand of politics that shakes things up rather than a calm and steady style of leadership, has seemed especially erratic, spinning out wild conspiracy theories, provoking racial and religious divisions and employing messianic language about himself.
He has also veered wildly on policies lately, reversing himself over the past week alone on gun control, tax cuts and foreign aid. He even abruptly called off a trip to Denmark out of pique that its prime minister would not sell Greenland.
“Is Trump really losing it, or is this just more of the same, but more?” asked Russell Riley, a presidential scholar at the University of Virginia’s Miller Center. “Democracies don’t get into serious trade disputes with authoritarian regimes because, presumably, democrats know out of the box that when things get tough, they don’t have at their disposal the tool of last resort for the autocrat: a command economy.”