In a rare bipartisan move, two senators have introduced legislation in the latest attempt to fight the flow of fentanyl and its precursors into the United States from China, Mexico and through other borders — one reason that President Donald Trump has given for his new tariffs.

Beijing will "resolutely counter" U.S. pressure on tariffs and the fentanyl issue, China's foreign minister said on Friday, adding that major powers "should not bully the weak", in a veiled swipe at the Trump administration's foreign policy.

Trump during his address to Congress said that Canada and Mexico ‘have allowed fentanyl to come into our country at levels never seen before.’

The White House announced on Monday that it will impose increased tariffs on China, citing the ongoing fentanyl crisis in the U.S. as the driving force behind the move.

A lack of trust and the whack-a-mole nature of stamping out the chemicals used to make the drug help explain why the war against fentanyl has been so intractable.

BEIJING (AP) — Chinese Foreign Minister Wang Yi said China will continue to retaliate for the United States’ “arbitrary tariffs” and accused Washington of “meeting good with evil” in a press conference Friday on the sidelines of the country’s annual parliamentary session.

China's commerce ministry criticized the U.S. for imposing 20% tariffs on Chinese goods due to the fentanyl issue, calling it an act of protectionism and bullying. The ministry urged the United States to stop shifting blame and address its own fentanyl problem objectively.

The president said the flow of the illicit opioid is one of the reasons for imposing tariffs on trading partners.