Why does Trump blame Mexico so much?

The administration of the current US President Donald Trump has not been getting the needed co-operation it wants from Mexico especially on the issue of the proposed wall to be built at the southern border that has been the operational ground for drug smugglers and illegal immigration. The Mexico government has been reluctant towards the project as Trump wants them to also pay for the wall.

Donald Trump has several times threatened to impose tarrif on Mexico or close the US-Mexico border if illegally activities of the cartels by smuggling drugs into the United States do not stop. The threat is intended to push the Mexican government towards sustaining the international war on drugs dealers, but honestly the Mexican government has indeed tried their best to put a stop to the activities of drug smuggling into the United States but it seems the war declared on drug cartels is not yielding the desired results.