Danielle Allen is a political theorist at Harvard University and a contributing columnist for The Post.

While we’re on the subject of Vladi­mir Putin, it’s worth noting another way Russia is working against U.S. interests. Russia is helping to sustain the war on drugs. In fact, Russia has become the world’s most aggressive defender of maintaining the war on drugs, outdoing even countries such as Iran. Iran, for instance, supports things such as needle exchanges for heroin users; Russia does not. And Russia’s hard-line stance on the drug war is bad for us.

The contrast with a country like Iran means that Russia’s social conservatism is an insufficient explanation for its stance. To understand its motives, we need to look elsewhere. One reason for Russia’s aggressive position on the war on drugs may be that members of the Russian oligarchy appear to be profiting from the illegal drug economy. A second reason must surely be that Russia can see clearly that modern prohibition is weakening the United States, its historical geopolitical competitor.

How does Russia make its influence felt in ways that matter for the rest of us? The current executive director of the U.N. Office on Drugs and Crime is Yuri Fedotov. Fedotov was the Russian ambassador to Britain during the polonium poisoning in London of Alexander Litvinenko. As Samuel Oakford has reported for Vice news, Litvinenko, shortly before his death, completed a report alleging links between Viktor Ivanov, recent Russian drug czar and confidant of Putin, and St. Petersburg-based mafia at a time when those organizations were involved in drug trafficking. The complex structure of corruption in Moscow makes it challenging to probe the significance of such connections, but for whatever reason, the Russians have used their role at the U.N. Office on Drugs and Crime and on the U.N. Security Council to block reform.

In April, for the first time since 1988, the United Nations held a special session of the General Assembly on global drug policy. In the intervening decades, powerful movements for reform have developed in South and Central America, in Europe, and also here in the United States. Uruguay is about to begin implementing the first legal national-level state sale of marijuana. Mexico is in the process of liberalizing its marijuana laws. Portugal has legalized marijuana, decriminalized other drugs by making use of them subject to administrative fines instead of criminal penalties, and embraced a policy of harm reduction, which refers to the effort to reduce the harms that flow from drug use instead of trying to achieve an end to drug use. For reformers, one of the main goals for the General Assembly special session was to have language supporting harm reduction, decriminalization and an acknowledgment of the failure of the drug war included in the U.N. protocols. Russia succeeded in blocking these efforts.

While individual countries will go their own way and pursue reform at the national level, the continuance at a global level of the language of prohibition and a focus on a criminal justice instead of a public-health strategy for narcotics control will slow reform. Domestic arguments about whether harm reduction, legalization and decriminalization make sense will unfold against a backdrop of international protocols where those ideas have not been endorsed.

But what does Russia get out of slowing down efforts to end the war on drugs? A Brookings Institution report by New York University scholar Mark Galeotti calls out corruption in the Russian Federal Security Service forces and a tendency on the part of Russians to view international law enforcement through the lens of geopolitical rivalries and as a tool for “asserting regional hegemony.” Legal methadone clinics, so the argument runs, according to Oakford, would undercut an important source of revenue for Russian drug-trafficking organizations involved in corruption networks with the security forces.

And what about the geopolitical stakes? Russia believes that its heroin problem was caused, even perhaps intentionally, by the United States with the destabilization of Afghanistan. But Russia can also surely see that the war on drugs is weakening the United States. Every year Americans of all races collectively spend $100 billion to buy illegal drugs. As a country, we then bear costs of roughly $100 billion a year from fighting the crime related to illegal drugs and from the loss to productivity caused by incarceration. Our national defense budget, by way of contrast, is $600 billion a year. If you want a competitor to be thrown off focus by a distraction, a project that drains its resources at this scale annually would seem welcome.

Then there is the social division spawned by the war on drugs. The burdens of mass incarceration and the increased capacity of the police for violence have fallen most heavily on African Americans and Latinos, despite the equal-opportunity use of drugs by whites, blacks and Latinos. The combined impact of racial disparities in mass incarceration and in the application of police force has now, in 2016, brought about the most severe racial split that our country has seen in a long time.

This racial division isn’t merely depressing and dispiriting. It isn’t merely material for politicians from either party to exploit. It also weakens us as a country. Any country where citizens are engaged in intense conflict and controversy among themselves has a reduced capacity to play an impactful role in the world. What the war on drugs has done to us is good news for Russia.

And here it is worth remembering that “law-and-order” Donald Trump would double down. When Trump invokes his mighty wall on the Mexican border, he often extols as a virtue that it will keep the drugs out. Every time I hear crowds chant, “Build the wall,” I can’t help but think about the all the tunnels that international drug traffickers have already constructed underneath our border. A Trump wall would go up; the web of drug tunnels would go under.

At this point, our situation is already crystal clear. The drug war is not solving the problems of either addiction or crime. It is, however, tearing our social fabric, and that weakens us as a country, including within the geopolitical order. Trump and Putin are on the same page here. With regard to the war on drugs, they are aligned in pursuing a policy that makes America weaker.