Trump cited the fentanyl issue as the reason for imposing a 10% tariff on all Chinese imports in early February, on top of any existing duties. He doubled that to 20% earlier this month. He also has cited fentanyl, along with other reasons, for imposing tariffs on Canada and Mexico.

China said on Wednesday that the U.S. has undermined bilateral counter-narcotics cooperation by imposing tariffs on Chinese goods over fentanyl, calling on Washington to stop using the issue as a bargaining chip to "blackmail" the country.

Officials from China’s Foreign Ministry and the Ministry of Public Security said in a briefing the country has achieved success in controlling the drugs and done all it can for the U.S.

China is willing to do more to address U.S. concerns about illicit fentanyl trade, an official from the Ministry of Foreign Affairs told reporters Wednesday.

Canadian and Chinese officials say they were already helping reduce fentanyl smuggling. Prime Minister Justin Trudeau said fentanyl crossing the northern border is "near zero."

Reuters, the news and media division of Thomson Reuters, is the world’s largest multimedia news provider, reaching billions of people worldwide every day. Reuters provides business, financial, national and international news to professionals via desktop terminals, the world's media organizations, industry events and directly to consumers.