Because this question is tied to the policies and executive actions taken by the United Nations in response to the War on Drugs, we can consider what specific plans this agency has committed itself to. In 2016, the UN General Assembly produced a document, linked below, outlining the steps its member nations would take to counter and prevent the world drug problem. We might think about some of their considerations.
1.) Regarding the prevention of drug abuse, the UN has maintained that programs directed at discouraging consumption via programs to educate the youth and general public are particularly effective. For example, the agency believes that by creating new recreational facilities and improving public spaces, both the youth and adults can be encouraged to engage in healthier lifestyle choices, participate in community activities, and exchange their culture and experiences with one another. The promotion of such a dynamic and desirable public sphere should be strong and provide individuals with alternative activities and forms of self-expression than engaging in drug abuse.
2.) Regarding the prevention of drug-related crime and punitive action, the UN has established measures to strengthen the multidisciplinary structure of international organizations devoted to this purpose. Efforts have been made to evaluate the socioeconomic conditions within member states and in regions lying outside of UN jurisdiction in order to determine those factors that might facilitate organized crime and the manufacture of drugs. With the collection of this information and its distribution to all cooperating governmental agencies, the UN hopes to combat the supply side of the drug problem while simultaneously ameliorating those domestic conditions that permit its encroachment in the first place.
3.) The UN has also committed itself to stopping the spread and use of psychoactive substances (including methamphetamine), which have become the greatest threat to public health in recent years. The global SMART program, as well as relevant International Narcotics Control Board tools, such as Project Prism, have been used to great effect in identifying and preventing the distribution of amphetamines in particular. SMART is a global community of support groups offering assistance to those attempting to overcome narcotics addiction, and it has exerted tremendous influence not only over the lives of former amphetamine abusers but also in helping reshape the global perception of abusers and the process of recovery itself. Programs like SMART that cultivate a healthy, public dialogue about the need for such organizations removes the stigma of drug abuse and reduced demand overall.
These points should help you get started thinking about how the UN (or any other major institution) might address the global drug epidemic.