WASHINGTON, D.C. — Mexican transnational criminal organizations (TCOs) have significantly increased opium production and shifted their operations to expand heroin trafficking in recent years. The TCOs launched a concerted effort to make the illicit drug readily available to Americans as the number of heroin overdose deaths in the U.S. surge, reports the Drug Enforcement Agency (DEA).

America’s southern neighbor was also identified in the DEA report as the primary source of clandestinely-produced fentanyl, a synthetic opioid that is an estimated 80 to 100 times more potent than morphine, and 25 to 40 times stronger than heroin.

Fentanyl, which is often added to heroin to increase its effects, has also been linked to hundreds of deaths in the United States in recent years.

“Mexico is the primary supplier of heroin to the United States. Opium poppy cultivation in Mexico has increased significantly in recent years reaching 17,000 hectares in 2014, with an estimated pure potential production of 42 metric tons of heroin,” reveals the DEA in its 2015 National Drug Threat Assessment. “This increase was driven in part by Mexican organizations shift to increased heroin trafficking.”

DEA notes that “the potential production of 42 metric tons may be an overestimate or an underestimate of the actual figure. There are no recent, reliable crop yield studies of opium poppy in Mexico, thus it is impossible to estimate potential heroin production in Mexico with high confidence.”

Heroin is made from the resin of opium poppy plants.

The increase in opium poppy cultivation by Mexican drug cartels comes as the number of heroin overdoses in the U.S. have skyrocketed.

Heroin overdose deaths have “increased significantly” in many cities across the U.S., particularly in the Northeast and areas of the Midwest, rising 244 percent between 2007 (2,402) and 2013 (8,257), points out the drug threat assessment.

That means deaths linked to heroin, which are increasing at much faster rate than for other illegal drugs, have more than tripled between 2007 and 2013.

Meanwhile, the DEA report notes that “Mexican traffickers are making a concerted effort to increase heroin availability in the US market.”

“Heroin use and overdose deaths are likely to continue to increase in the near term…The drug’s increased availability and relatively low cost make it attractive to the large number of opioid abusers (both prescription opioid and heroin) in the United States,” it adds.

Most of the heroin brought into the U.S. by Mexican drug cartels is trafficked across the Southwest border where seizures of the illegal substance have been rising.

“Seizures at the Southwest Border are rising as Mexican TCOs increase heroin production and transportation,” notes DEA. “Heroin seizures at the border more than doubled over five years, from 2010 (1,016 kilograms) to 2014 (2,188 kilograms), most likely due to increased Mexican heroin smuggling and enhanced law enforcement efforts along the border.”

“Most heroin smuggled across the border is transported in privately-owned vehicles, usually through California, as well as through south Texas,” it continues.

Across the United States, heroin seizures have increased 81 percent over five years, from 2,763 kilograms in 2010 to 5,014 kilograms in 2014, according to the National Seizure System (NSS) data.

“Traffickers are also transporting heroin in larger amounts,” notes DEA. “The average size of a heroin seizure in 2010 was 0.86 kilograms; in 2014, the average heroin seizure was 1.74 kilograms.”

Furthermore, the report reveals that “DEA heroin arrests nearly doubled between 2007 (2,434) and 2014 (4,780).”

The smuggled heroins is commonly milled by drug cartel members in the U.S.

Mexican TCOs are identified as the “greatest criminal drug threat” facing the United States, adding that “no other group can challenge them in the near term.”

The cartels have also been linked to clandestinely-produced fentanyl.

“Clandestine fentanyl is illegally manufactured in clandestine laboratories, primarily in Mexico,” reports DEA. “Clandestine fentanyl is available throughout the United States, most commonly in white powder heroin markets. Fentanyl is added to heroin to increase its potency, or is mixed with diluents and sold as fentanyl or disguised as highly potent heroin.”

Criminals in Mexico obtain fentanyl analogs and precursor chemicals from distributors in China.

“Fentanyl and its analogs are responsible for more than 700 deaths across the United States between late 2013 and late 2014,” declares the DEA.

Mexican cartels are operating in cities across the United States. The area of influence of major Mexican TCOs extends to over 100 major cities within DEA field division areas of responsibility. That does not include rural and suburban where the DEA does not maintain a presence.

According to law enforcement reports, the Mexican trafficking groups are relocating from major cities to suburban and rural areas.

Highly sophisticated Mexican TCOs are the most significant drug trafficking organizations operating in the U.S.

“The foundation of Mexican TCO operations in the United States is comprised of extended family and friends. Families affiliated with various Mexican TCOs in Mexico vouch for US-based relatives or friends that are deemed trustworthy enough to help run various aspects of the drug trafficking operations in the United States,” reports DEA. “Actual members of Mexican TCOs are usually sent to important US hub cities to manage stash houses containing drug shipments and bulk cash drug proceeds.”

Mexican cartels continue to be the number one suppliers of cocaine, heroin, methamphetamine, and marijuana, says the DEA report, adding that they use U.S. gangs to distribute the illicit drugs.

The Sinaloa Cartel, led by fugitive drug kingpin Joaquin “El Chapo” Guzman, continues to be the largest supplier of illicit drugs in the U.S.