The purpose of the drone warfare program is to PERPETUATE the wars

The whole purpose of the drone warfare program is to terrorize local populations & kill some innocent civilians in order to recruit more Islamic Extremists to PERPETUATE the wars. 

That is it's undoubted effect. 
It is a major recruitment tool for the Islamists.

If it was not the deliberate aim to recruit more Islamic Extremists, the drone warfare program would be abandoned. 

A few years ago 25% of Pakistani's considered the American government their enemy. 
Now it is 92%. 
The most cited reason is the American drone warfare program. 

Other countries have also had a substantial increase in the level of support for Islamic Extremists. 
These countries include Libya, Egypt and Yemen.