UPDATE 1-Trump: 'You'll find out' how U.S. will respond to Iran

Asked how the United States will respond to Iran after Iran shot down an American drone, U.S. President Donald Trump told reporters, "You'll find out."

Trump called Iran's move a big mistake in remarks to reporters before a meeting with Canadian Prime Minister Justin Trudeau but kept open the possibility of talks with Iran. Trump also said the United States has documented that its drone was in international waters, not in Iranian territory, as Tehran has said.

Trudeau said he was very concerned about escalations in tensions with Iran.