So you set a lower moral threshold for acts your government carries out (or accepts are carried out in it's name) than for acts carried out by it's citizens. Isn't your government meant to be 'of the people' and shouldn't the same rules of moral behaviour therefore apply?
The difference between what the "government" can do and what an individual acting alone can do have nothing to do with different "moral thresholds".

For instance, a government can capture and imprison individuals suspected of doing wrong, an individual cannot.

A government can print more money when it runs out, individuals go to jail for the same act.

As for the argument of necessity, certainly there is a necessity to combat global terrorism, but do you think that the information gained from such techniques will be reliable enough to be useful in that cause
Any information given by a suspect, whether as the result of torture or not, must be corroborated by another source or it cannot be trusted. Proper interrogation techniques can often successfully work through the layers of cover stories and falsehoods.