When you declare war on drugs I find it illogical to only combat the suppliers. It is just unfortunate that the drugs trade is much too lucrative to end the war by only fighting drug cartels.
People do not only use drugs for recreational purposes; some use it because of peer pressure and others use it to escape reality. So if you also combat the causes that cause people to want to use drugs the war on drugs might become more effective.
Blaming the police of drugs flooding into the city is unproductive which might make them feel incompetent so it would be logical that they sink to the level that they plant evidence on 'known and / or suspected' drug traffickers so they at least feel that they have done something constructive.
Unfortunately this way they are only fighting the symptoms and not the cause.