This week, as headlines about Mr. Trump’s attempts to interfere in the special counsel’s Russia investigation once again swirled, the president’s irritation boiled over. In a meeting Wednesday night in the Oval Office, with Mr. Kushner dialing in from the Middle East, the president lost patience with aides he saw as slow-walking his request and decided tariffs would be going into effect.

The idea of punishing Mexico with tariffs had several key proponents, including Stephen Miller, Mr. Trump’s chief policy adviser and an immigration hard-liner. Pat Cipollone, the White House counsel, and Peter Navarro, a trade adviser, had also argued that emergency powers gave the president broad authority to impose the tariffs.

Among their arguments was that Mexico had done nothing to solve the problem and that it was unlikely to act without economic pressure. Tariffs, they argued, would hurt Mexico’s economy and put pressure on its government to finally take action.