Explained | Why it is so difficult to stop the flow of fentanyl into the US?

Thwarting the transport of fentanyl into the US poses significant challenges for both the United States and Mexico given the cartels' immense resources, the ease with which fentanyl is produced and moved and the insatiable demand for narcotics among US consumers.

Mexico City: When President Donald Trump threatened to impose steep tariffs on Mexico, Canada and China, he blamed these three countries for enabling the flow of fentanyl into the United States and fueling what officials have called a national emergency.

President Claudia Sheinbaum of Mexico swiftly pushed back on Trump's suggestions that her government colluded with drug traffickers, calling it "slander." And she also put the blame on the United States, arguing that the fentanyl crisis stemmed from immense domestic demand for drugs, including fentanyl, and the illegal sale of US guns to cartels.

Sheinbaum announced Monday that she had reached an agreement with Trump, who agreed to pause the tariffs as she promised to send 10,000 members of the National Guard to the US-Mexico border to stop the trafficking of fentanyl.

But thwarting the transport of the deadly synthetic opioid into the United States poses significant challenges for both the United States and Mexico given the cartels' immense resources, the ease with which fentanyl is produced and moved and the insatiable demand for narcotics among US consumers, analysts and experts say.

Given these factors, it may be extremely difficult for Mexico to demonstrate that it is meeting Trump's terms -- particularly within the 30-day window he allotted to delay the imposition of tariffs.

Fighting the cartels is hard, and often futile.

For over a decade, most of Mexico's efforts to tackle organized crime focused on targeting powerful leaders to weaken their grip on large swaths of territory.

But the strategy backfired. Engaging in direct confrontations and going after senior cartel members led to these groups splintering into smaller, disorganized and violent cells that caused even more bloodshed. While those actions were symbolic and put pressure on the criminal groups, analysts say, the strategy never focused on or intended to thwart the cartels' production capabilities. Instead, its goal was to stem the violence disrupting communities.

Mexico's previous president, Andrés Manuel López Obrador, came to office in 2018 promising a new approach: avoiding direct confrontation with the cartels in favor of addressing the root causes of criminality like corruption and poverty.

But his strategy, which he branded with the slogan "hugs, not bullets," did little to tame the extraordinary levels of violence or diminish the ever-expanding power of cartels that traffic drugs across the US border.

When Sheinbaum took office in October, she said she would continue López Obrador's focus on the social causes of the violence, while also working to lower rates of impunity and build up the national guard. In her first few months, she has taken a tougher line on organized crime, ramping up operations that have led to large seizures of fentanyl and a slew of arrests.

But analysts still question whether this can truly have a big effect.

One of the most prolific producers of fentanyl in Mexico is the Sinaloa Cartel, which traffics most of the fentanyl entering the United States. Given its vast financial, logistical and operational resources, the group has been able dominate production "with an impressive ease," said Alberto Capella, a security analyst and former police chief of the Mexican states of Quintana Roo and Morelos.

Capella added that even if Mexican authorities could seize every shipment of fentanyl before reaching the border, the root of the problem would not disappear.

"The problem is not the existence of Mexican cartels; it is the existence of a mass consumption and markets," said Capella. "If the mass market of consumers prevails, it will immediately lead to the emergence of suppliers to satisfy this mass consumption, whether it is fentanyl or any other drug," Capella added.

Chemicals coming from China are hard to regulate.

Given its robust chemical industry, China is the major supplier of the raw compounds, known as precursors, needed to produce synthetic drugs, including fentanyl and methamphetamines.

As the fentanyl crisis continued to take lives in the United States in recent years, the Biden administration sought more counter narcotics cooperation with President Xi Jinping of China to tackle the issue. Last year, China announced new regulations and tightened controls on the precursor chemicals, including increased government oversight on several chemicals used to make fentanyl.

Fentanyl deaths in the United States did drop in the last year. Yet Trump still issued a 10% tariff on all Chinese products Tuesday, the result of an executive order issued over the weekend aimed at pressuring Beijing to further crack down on fentanyl and precursor shipments.

But even more regulations may not bring significant results.

Some of the chemicals used to manufacture fentanyl are very common and are used in the production of plastics, perfumes, pharmaceuticals and more, making broad restrictions difficult.

Criminal groups are also now coming up with new methods and risky ways to maintain fentanyl production and potency, and to circumvent regulations.

Sinaloa Cartel members are, for instance, experimenting on animals and people to come up with potent concoctions, including mixing their formulas with substances like animal tranquilizers to keep people hooked.

The group is also luring chemistry students and professors to synthesize the chemical compounds, with the goal of sidestepping the need to import those raw materials from China.

Fentanyl is easy to transport, hard to intercept.

In the past five years, the amount of fentanyl crossing the border has increased tenfold, with Mexico being the source of almost all of the synthetic opioid seized by U.S. law enforcement in recent years.

Fentanyl is a potent and fast-acting drug that is highly addictive. It is 100 times more potent than morphine, which means a small quantity goes a long way: Two milligrams can kill you.

Because the synthetic opioid is so potent, it is shipped in small, compact packages that are easy to transport and hide, making them less detectable and harder to intercept. As opposed to other drugs like cocaine, marijuana and methamphetamine, which are regularly trafficked in tons, fentanyl is moved in kilos.

It takes only a small amount to make hundreds of thousands of laced pills. Even in small quantities, it is extremely profitable, meaning couriers can smuggle small amounts and make a considerable profit by hiding it in their vehicles, under their clothes or in backpacks.

Of the people smuggling synthetic opioids into the United States, most are not migrants illegally traversing the desert, swimming across the Rio Grande or moving through secret tunnels, as Trump has suggested.

The largest known group of fentanyl smugglers are Americans coming through legal ports of entry. More than 80% of the people sentenced for fentanyl trafficking at the southern border are US citizens, federal data shows.

The New York Times has found that cartels are recruiting thousands of Americans and turning them into fentanyl mules who can easily cross back and forth into the United States and carry the drug mostly in their private cars.

Almost all the fentanyl found at the southern border arrives in cars and just 8% of private vehicles that cross are scanned for drugs, according to Customs and Border Protection.

Fentanyl is easy to make; it can be cooked in small kitchens.

Whereas methamphetamine needs large laboratories and specialized equipment to produce, fentanyl can be made in small kitchens and makeshift labs using rudimentary cooking utensils.

Times reporters gained access last year to a fentanyl lab in the state of Sinaloa, where there is a turf war underway between rival factions of the Sinaloa cartel.

They witnessed firsthand how the deadly opioid was made in a small kitchen using an immersion blender and cooking pans. In one single batch, the cooks were making 10 kilos, an amount that can reap a profit of up to $6.4 million, according to US prosecutors.

Cooks and operatives affiliated with the cartel have revealed in interviews that since the conflict erupted in September, Sheinbaum has deployed hundreds of soldiers to Culiacán, the capital of Sinaloa, to combat violence and fentanyl production. This escalation has led to increased arrests and the dismantling of laboratories, forcing them to frequently relocate out of fear of detention.

Still, fentanyl is so incredibly profitable that it is just too good to pass on, cooks and senior members of the Sinaloa Cartel have said, making it highly unlikely that they will stop producing what they consider a miracle product.

As one cook said: "This is what makes us rich."