The question now is whether Beijing will fully weaponize its currency, allowing it to significantly weaken in value versus the American dollar. That could prompt a harsh response from Trump administration officials who have already warned China against that course.

It could also ripple across the globe, forcing countries that compete with China to consider devaluing their own currencies. That could lead to a zero-sum spiral of devaluations that would damage global growth and lead to even more trade protectionism, threatening the world’s economic integration.

“It’s hugely significant as they are making a clear choice to do this,” said Michael Every, head of financial markets research in Asia for Rabobank, referring to China’s central bank. “This is going to escalate rapidly and badly.”