Stopping the flow of fentanyl into the United States has been cited as one of the major reasons President Donald Trump slapped a new round of tariffs on Mexico, Canada and China.
Mr Trump said the 25 per cent tariffs on Mexican and most Canadian imports were also designed to pressure the two countries to do more to curb illegal immigration to the US.
The tariffs on the US's largest trading partners and the additional 10 per cent tariff on goods from China will start on Tuesday, US time.
So where does illegal fentanyl in the US actually come from?
And will tariffs do anything to stop the drug killing Americans?
What is fentanyl — and how bad is the US epidemic?
Fentanyl is a potent synthetic opioid drug that is approved for use as pain relief and for anaesthetics in medical settings.
It is approximately 100 times more potent than morphine and 50 times more potent than heroin as an analgesic, according to the US Drug Enforcement Administration.
However, fentanyl has also become a popular illicit drug and is one of the highest causes of drug overdose deaths in the US.
"It is a major crisis in this country," said Miami University sociologist Rodney Coates.
The latest data from the US Centers for Disease Control and Prevention (CDC) showed there were 89,740 fatal overdoses from fentanyl and all other street drugs in the 12 months to August 2024.
The figure represented a 21.7 per cent decrease in such deaths in the US compared to the previous 12-month period, and was significantly lower than the "250,000-300,000" Mr Trump erroneously claimed in January.
Still, Professor Coates said the scale of the fentanyl crisis remained "horrendous".
Where does illegal fentanyl in the US come from?
According to security analyst Vanda Felbab-Brown, most of the finished fentanyl products imported into the US come from two Mexican cartels which make the drug with "precursor chemicals" from China.
Precursor chemicals are more elemental chemicals from which fentanyl is manufactured, said Dr Felbab-Brown, who directs a synthetic opioids project at the Washington-based Brookings Institute.
"There is very little fentanyl that comes from China to the US in a finished form," she said.
The US Drug Enforcement Administration did not respond to interview requests for this story, but information on the drug authority's website confirmed Dr Felbab-Brown's explanation.
The administration's website explains that precursor chemicals are typically sent from China to Mexico, where they are used to manufacture powder and pills in clandestine labs.
The deadly drug is then smuggled into the US via land, sea, air and underground routes and distributed by local criminals.
Canada's role in the fentanyl trade into the US was not clearly explained in the White House statement on Mr Trump's rationale for the new tariffs.
It simply pointed to the "growing presence of Mexican cartels operating fentanyl and nitazene synthesis labs in Canada".
Nitazenes are a deadly synthetic opioid that can be stronger than fentanyl and hundreds of times more potent than heroin.
But Dr Felbab-Brown said fentanyl was not imported to the US from Canada.
"In fact, Canada's fentanyl market is huge and very devastating. But it's completely separate from the US fentanyl market," she said.
Canadian Prime Minister Justin Trudeau has presented recent data showing that only about 1 per cent of fentanyl in the US originates in Canada.
What has the US done previously?
Experts say this is the first time the US has imposed tariffs on Canada and Mexico over drugs and immigration, but US tariffs on China started in 2018 during Mr Trump's first presidency.
China introduced stronger regulations on fentanyl in 2019, officially scheduling fentanyl-related substances as a class of drugs.
As the relationship between Beijing and Washington deteriorated over the ensuing years, so too did cooperation on drugs.
But in 2023 the Biden administration had a breakthrough with Chinese President Xi Jinping, and the two countries restarted anti-fentanyl cooperation.
The Australian Strategic Policy Institute's director of national security programs John Coyne said that while China did clamp down on some precursors, its deal with the US did not go far enough.
"At the end of the day, what needs to happen is the CCP [Chinese Communist Party] needs to regulate and do compliance monitoring of its chemical and pharmaceutical industry and be good international citizens," he said.
"If they wanted to, they could stop the flow of precursors and synthetic opioids to North America."
Will tariffs on Mexico, Canada and China stop illegal fentanyl entering the US?
Experts said it was unlikely tariffs would curb the flow of illegal fentanyl into the US and address the drug crisis, even if Mexico and China successfully clamped down on their part in the trade.
Dr Coyne said organised crime groups such as those sending fentanyl to the US regularly changed their methods.
"We all know that Mexican cartels are particularly challenging," he said, adding that they were well-connected and violent.
Drug manufacturers could reroute their finished products via other countries, the Brooking Institute's Dr Felbab-Brown said.
If fentanyl cooks in Mexico had trouble getting precursors from China, she said, new suppliers in other locations such as India would be available.
Miami University's Professor Coates agreed and also questioned Mr Trump's move to quash illegal immigration to the US.
He said these individuals played an important role in the US economy, often working in low-paid jobs in service industries such as hospitality.
"If you stop the flow of immigrants and send them all home, what that's going to do with the price of everything from our agriculture, building, landscaping, a whole bunch of service jobs?" he said.
How have Mexico, Canada and China responded?
Canada responded with tariffs on $US170 billion ($277 billion) worth of American goods.
Mexico is still working through how it will respond, while China is preparing to take the US to the World Trade Organization to reverse the tariffs.
A Foreign Ministry spokesperson reiterated Beijing's position that "trade and tariff wars have no winners".
"China calls on the US to correct its wrongdoings, maintain the hard-won positive dynamics in the counter-narcotics cooperation, and promote the steady, sound and sustainable development of China-US relationship," the spokesperson said.
The new tariff orders against China, Mexico and Canada all contain clauses suspending a duty-free exemption for low-value shipments below US$800.
The exemption was widely seen as a loophole that allowed shipments of fentanyl and its precursor chemicals into the US.
Such small shipments often avoid screening at ports of entry, allowing shipments of drugs and their ingredients to enter undetected.
ABC/Reuters
