[Talk-ko] Someone is removing "sensitive" information

[Max]

Just stumbled upon tha the NIS headquarter and some other objects have 
been deleted again. That's at least the 3rd time now.

user woodpecker has already left a message on some of the changesets.

Comment from woodpeck 12 days ago

Hello, in this changeset you deleted y couple of buildings and your 
comment says that you deleted them because they are in a security area. 
However, OSM does not generally respect specific national security 
interests with regards to mapping. If a building is visible on aerial 
imagery, then it may be mapped in OSM, no matter whether it is in a 
security area or not. Deleting such a building, as you have done here, 
can be interpreted as an act of vandalism on OSM. Please don't do that.

Some of the affected changesets:

https://www.openstreetmap.org/changeset/46159152
https://www.openstreetmap.org/changeset/46159124 
https://www.openstreetmap.org/changeset/46159152 
https://www.openstreetmap.org/changeset/46159410 
https://www.openstreetmap.org/changeset/46159815 
https://www.openstreetmap.org/changeset/46159870 
https://www.openstreetmap.org/changeset/46159916

probably more.

the changeset comment is 건물삭제(보안구역) which translates to Removing 
buildings (Restricted areas)

Questions:
1. what are good tools to find more of this?
2. what are the right steps to do if vandalism like this is detected?
3. can this be avoided in the future?
4. is there a tool to get notified if someone changes a specific area?
5. who has authority to revert? should I try to do this, but I might 
miss something.