BEIJING (Reuters) -China's state media warned U.S. President-elect Donald Trump his pledge to slap additional tariffs on Chinese goods over fentanyl flows could drag the world's top two economies into a mutually destructive tariff war.

Tariffs look set to be at the heart of Trump’s economic policy and the billionaire made it clear he wants his economic team to hit the ground running in January.

"When a country (USA) is losing many billions of dollars on trade with virtually every country it does business with, trade wars are good, and easy to win," reads a tweet from President Trump in March 2018.