U.S. President-elect Donald Trump's vow to impose tariffs on China and Mexico unless they stem the flow of fentanyl and migrants across the U.S. border could impel deeper cooperation from those governments on drug policing, experts said.

But the threat also carries risk, particularly concerning U.S.-Chinese collaboration on fighting fentanyl, which has improved this year after bilateral negotiations between U.S. President Joe Biden and Chinese President Xi Jinping.

In social media posts on Monday, Trump promised to impose additional 10% tariffs on Chinese imports and 25% tariffs on Mexican and Canadian goods — the United States' three largest trading partners — and asserted that not enough was being done to stop drugs and migrants from entering the country.