President Donald Trump said there may be “pain” in making America “great again” when he defended his decision to impose tariffs on imports from Canada, Mexico and China in a Truth Social post on Sunday.

Tariff retaliation: Mexico and Canada immediately vowed to impose tariffs of their own. The Canadian prime minister, Justin Trudeau, announced retaliatory tariffs starting with 25 percent tariffs on approximately $20 billion worth of U.S. goods on Tuesday, with $85 billion more to follow within three weeks.

China's sharpest pushback on Sunday was over fentanyl, an area where the Biden administration had also been urging Beijing to crack down on shipments.

Long term US allies such as Canada and Mexico have reacted with fury over Trump's tariffs which the Wall Street Journal described as "the dumbest trade war in history"

U.S. President Donald Trump warned on Monday he might increase tariffs on China beyond the 10% he imposed on Saturday and that "we will speak to China" probably over the next 24 hours.

President Donald Trump announced steep tariffs on China, Canada and Mexico that risk igniting a trade war that could significantly damage the economies of the targeted countries and the United States.

Officials in China have vowed unspecified countermeasures in what could become a trade war after President Trump’s proposed 10% tariffs on all Chinese goods. NBC News’ Janis Mackey Frayer reports from Beijing on China’s reaction.