What to know as President Donald Trump imposes steep new tariffs on imports from Canada, Mexico and China, prompting retaliation and countermeasures.

Stocks in the US dropped Monday morning, following European and Asian markets lower as investors digested Trump's tariff announcements.

Trump's tariffs on Canada, Mexico and China suggest he is willing to risk a global trade war. The main thing that could stop him would be a stock market selloff.

Investors bought dollars, sold stocks and fretted about inflation on Monday in a scramble to assess the risk of trade war after Donald Trump put tariffs on top U.S. trading partners.

Business groups, economists and even some Republicans cautioned that new tariffs on goods from Canada, Mexico and China could undercut U.S. industry and the economy.

The White House said on Monday it has noticed that Mexico is "serious" about President Donald Trump's executive order on tariffs, but Canada has "misunderstood" it to be a trade war between the neighboring countries.

The president’s trade assault, which makes no distinction between ally and adversary, is an assertion of U.S. dominance with significant risks.

U.S. futures and global stocks were hit by a selloff early on Monday as markets around the world braced for a potential trade war triggered by President Donald Trump’s decision to impose sweeping tariffs on imports from Canada, Mexico, and China—which he acknowledged will cause “some pain” for American consumers.

A growing number of countries, including American allies, are striking trade deals as the Trump administration erects a higher fence around its global commerce.

Trump knows the United States has more leverage over its neighbors than they do over his country. But exploiting that position of strength could cause a historic rupture.