China and Mexico refuted U.S. President-elect Donald Trump's tariff threats, saying that cooperation and mutual understanding instead of tariffs could address the U.S.'s fentanyl concerns.

Trump said he will impose 25 percent tariffs on all goods entering the U.S. from Canada and Mexico on his first day in office, saying they will remain in place until the two countries "solve" the issue of illegal migrants and drugs crossing their borders into the United States.

Trump also said the U.S. "will be charging China an additional 10 percent tariff, above any additional tariffs, on all of their many products coming into the United States of America" for its alleged failure to curb the number of drugs entering the country.

Liu Pengyu, spokesperson for the Chinese Embassy in the U.S., said in a statement on Tuesday that China had taken steps to combat drug trafficking after an agreement was reached last year between leaders of both countries.

"The Chinese side has notified the U.S. side of the progress made in U.S.-related law enforcement operations against narcotics," Liu said. "All these prove that the idea of China knowingly allowing fentanyl precursors to flow into the United States runs completely counter to facts and reality."

A Chinese Foreign Ministry spokesperson also said on Tuesday that the U.S. should cherish the goodwill of China and safeguard the hard-won positive situation of China-U.S. cooperation on drug control.

China is one of the world's toughest countries on counter-narcotics, both in terms of policy and implementation, the spokesperson said.

"As early as 2019, China officially scheduled all fentanyl-related substances. It is the first country in the world ever to do so," the spokesperson said, adding that China has carried out extensive and in-depth counter-narcotics cooperation with the U.S., which has been highly productive.

The spokesperson said that China is ready to continue counter-narcotics cooperation with the U.S. on the basis of equality, mutual benefit and mutual respect.

Mexican President Claudia Sheinbaum read out a letter she said she would send to Trump in her morning news conference on Tuesday.

Noting neither threats nor tariffs would solve the "migration phenomenon" or drug consumption in the U.S., Sheinbaum said that what was required instead was cooperation and mutual understanding.

The Mexican leader also warned that should Trump go ahead with the tariffs, Mexico would retaliate by imposing its own taxes on U.S. imports. And that, she said, would "put common enterprises at risk."

Vanda Felbab-Brown, a senior fellow at the Brookings Institution and an expert on global drug policy, told the New York Times that "an imposition of tariffs is not going to do anything regarding the flow of fentanyl."

"In fact, it might undermine the counter-narcotics cooperation that the U.S. and China have been doing in 2024 and that came after no cooperation for over two years," the expert added.

(With input from agencies)