New Delhi, Jan. 21 -- President Donald Trump's pledge to provoke a sweeping tariff fight with Europe to get his way in taking control of Greenland has left many of America's closest allies warning of a rupture with Washington capable of shattering the NATO alliance that had once seemed unshakable.

The European Union's top official on Tuesday called Trump's planned new tariffs on eight of its countries over Greenland a "mistake" and questioned Trump's trustworthiness. French President Emmanuel Macron said the EU could retaliate by deploying one of its most powerful economic tools, known colloquially as a trade "bazooka."

The rising tensions concerning Greenland, and threats of a deepening trade war between the U.S. and Europe, caused glo...