China summons U.S. ambassador to protest Trump signing Hong Kong bill

• China's action came soon after the Chinese Foreign Ministry warned it would take "firm counter measures" if the U.S. continued to "interfere" in Hong Kong, per the New York Times.

What they're saying: A Chinese Foreign Ministry statement said the country's Vice Foreign Minister Le Yucheng told Ambassador Terry Branstad the U.S. bill marked a "serious interference in China’s internal affairs and a serious violation of international law," AP reports.

• "We are officially telling the U.S. and the handful of opposition politicians in Hong Kong who follow America’s lead to not underestimate our determination to protect Hong Kong’s prosperity and stability, don’t underestimate our belief to protect the 'one country, two systems policy,'" the foreign ministry said in an earlier statement, translated by CNBC.
• "And don’t underestimate our capabilities and strategies in protecting our country’s sovereignty, safety, growth and rights."

Go deeper: Pro-democracy parties triumph in key Hong Kong elections

Editor's note: This article has been updated with new details throughout.