Primarily InterServices Intelligence.This composes of personnel who belong to one party or other.Depending on who comes to power, particular group becomes active and powerful.Also there are moderate Muslims and hard liners.This is another mix.There is another group which wants the Army to control the country.
Hardline fundamentalists have a field day by projecting themselves as Martyrs of Islam.They command the loyalty of a section of Politicians.
Politicians have time only to be corrupt and wheeling and dealing; they will take any line to bring them to power.
To this medley is Pakistan’s strategic location and its proximity to China. West and US play a part in stirring the cauldron.Any or all the elements combine with any or all of the other groups.Depending on expediency and their writ runs.
The calyst and eventually the controlling force is terrorists.They are not a separate class. Any of the groups or a combiantion of the groups, control Pakistan,aided and abetted by the terrorists.
In effect, no body, least of all Pakistanis, know who is controlling Pakistan.