Scouting
Reconnaissance, Secret Investigation
noun, する verb
Inside spying is when you get inside enemy territory and spy on them. This is scouting and reconnaissance.
ないてい
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
警察はどんな時に内偵捜査をするのですか。
When do the police conduct their secret internal investigation?