Speaking to an audience in New Hampshire this week, President Trump announced a redoubling of the nation’s efforts to confront the opioid overdose crisis plaguing the country. Lost in all of the anguish over rising deaths from heroin and fentanyl is the fact that a “golden oldie” for substance abusers is making a comeback.

In February, the Oregon Health Authority reported methamphetamine-related deaths in 2016 exceeded those during the peak of the meth crisis of the early 2000s. The deaths attributed to methamphetamine rose from 51 in 2012 to 141 in 2016. By comparison, deaths in Oregon from heroin and fentanyl overdoses dropped during that same period.

The surge in methamphetamine-related deaths is not unique to Oregon. It has been an under-reported phenomenon affecting the entire country for several years now. This should surprise no one. Prohibition never shuts down a market for a substance or activity. It merely drives it underground and makes it more dangerous in the process. The war on meth is merely one of many fronts on which the larger war on drugs is being waged.

Methamphetamine, or desoxyn, occasionally used to treat Attention Deficit Hyperactivity Disorder, narcolepsy, and obesity, has been around since the early 20th century. It became a target in the war on drugs in 1971.

By the 1960s, it became popular for recreational and other nonmedical uses. In 1971, after President Richard Nixon declared a war on drugs and Congress passed the Controlled Substances Act, methamphetamine was classified as a Schedule II drug. Nonmedical use was made illegal. This created a new market for illegal drug dealers. Meth labs, using the popular and effective nasal decongestant Sudafed as an ingredient, sprang up throughout the U.S. and Mexico. As is usually the case with drug prohibition, more potent forms of the drug were developed and trafficked.

Responding to the surge in meth-related deaths, Congress next passed the Combat Methamphetamine Act in 2005. This made Sudafed only available “behind the counter,” with customers limited to only 7.5 grams per month. Pharmacies were required to track sales. Some states, such as Oregon and Mississippi, went even further, making the drug available only by prescription. Meanwhile, Drug Enforcement Administration teams combed the country in search of meth labs to attack.

This interruption in the supply chain led to a temporary drop in meth deaths. But the disappearance of domestic meth labs also created a vacuum quickly filled by Mexican cartels. And when the Mexican government cracked down on Sudafed, it wasn’t long before market forces drove the cartels to switch the ingredient to phenyl-2-propanone, or P2P.

The numbers show that the crackdowns aren’t working. The National Center for Health Statistics reports that the percentage of drug overdose deaths involving methamphetamine increased from 5 percent in 2010 to 11 percent in 2015. There were nearly twice as many meth-related deaths in 2014 as in 2010, and the number jumped another 30 percent in 2015. U.S. Customs and Border Protection statistics show seizures of meth tripling in the last 5 years. And overdose death rates have been steadily creeping back up while the price of meth has been trending down. A DEA spokesman believes the price per pound has been plummeting as manufacturers have improved their techniques.

Pointing out that substance abuse should not be viewed in isolation, Portland’s health officer reported that “80 or 90 percent” of the city’s heroin users are also using meth. This point requires greater emphasis because it relates to current opioid policy. Most policymakers address the opioid overdose problem mainly by cracking down on doctors providing opioids to their patients in pain. The majority of overdoses, however, are the result of non-medical users accessing the illicit market — and upwards of 90 percent of opioid overdoses involve multiple drugs, such as heroin, cocaine, methamphetamine, and alcohol.

Meth’s comeback shows why waging a war on drugs is like playing a game of “Whack-a-Mole.” The government cracked down on Sudafed (affecting millions of cold and allergy sufferers) while SWAT teams descended on domestic meth labs, and Mexican cartels popped up with a cheaper and better manufacturing system. In the case of opioids, authorities reduced opioid prescription and production, and nonmedical users migrated over to more dangerous heroin and fentanyl, driving up the overdose rate.

As they realized in Portugal in 2001, and recently grasped in Norway, the war on drugs is the major source of drug-related deaths. Portugal reached an armistice in its war. The Portuguese decriminalized all drugs and focused efforts on providing rehab services, safe syringe programs, and medication-assisted treatment. They now have the lowest opioid overdose rate in Western Europe and have seen a 75 percent reduction in the number of heroin addicts.

The U.S. should learn from this. It should also learn from its mistakes. Instead of waging war, the focus should be on treating those who want help and reducing the risk of overdose and disease for those who continue to use and abuse drugs.

Dr. Jeffrey A. Singer (@dr4liberty) practices general surgery in Phoenix, Ariz., and is a senior fellow at the Cato Institute.