Beijing has described cannabis legalization in North America as a “new threat to China” after reporting an increase in marijuana being trafficked into the country.

Liu Yuejin, deputy director of the China National Narcotics Control Commission, blamed liberalization of marijuana laws in Canada and vast swathes of the U.S. for fuelling an increase in the amount of cannabis smuggled across its borders. He said this has led to a spike in domestic consumption, claiming that there are now 24,000 cannabis users in China.

The country’s leading drug enforcement authority said this represents a year-on-year rise of 25%, although 24,000 cannabis users seems like an extreme underestimation considering there are more than 1.4 billion people in China and cannabis has been prevalent there for millennia.

Just last week, scientists revealed they had found the earliest known evidence of cannabis use in global history in tombs located in the Pamir Mountains in western China. They found traces of marijuana in wooden burners that many have been used during burial rituals.

The cannabis uncovered contained potent levels of THC, and the researchers speculated that people fired it up with hot stones and inhaled the resulting smoke.

Cannabis has been cultivated in East Asia for 4,000 years, but China’s government has a strict anti-marijuana policy.

Relations between Beijing and Washington are strained right now as a result of the trade war. The Trump administration has already imposed 25% tariffs on $250 billion worth of imports from China in order to force it to end perceived unfair trade practices.

It now plans to place the tariffs on a further $300 billion worth of goods, including clothing, toys, and housewares. Walmart and Target are among the 600 companies to write to the president to warn him that an escalating trade war will damage the U.S. economy, while Beijing has said it is “showing determination” as it makes “genuine battle preparations”.

Washington has also accused China of being the major source of the fentanyl ravaging America. The comments from the China National Narcotics Control Commission may add further fuel to the fire. The U.S. has not legalized cannabis at a federal level, although it is under pressure to do so.

“In two years, we have found increasing cannabis trafficked from North America to China,” said Liu.

He added that China intercepted 115 packages sent through international postal parcels, containing a total of 55 kg of cannabis in 2018. Most of the suspects were foreign students or Chinese students that had recently returned home.