Look at the map of ITU member states [1] and tell me where you'll find this spacefaring nation.
[1] https://upload.wikimedia.org/wikipedia/commons/3/33/Member_s...
"Taiwan, Province of China, is not listed separately in the UN M49 but included in China." [1]. It is an unofficial member, however, which is why you can dial +886 to get to Taiwan [2]. Practically speaking, with the U.S. providing Taiwan its security umbrella, enforcement mechanisms for a Taiwanese breach of ITU protocol would be straightforward.
[1] https://www.itu.int/en/ITU-D/Statistics/Pages/definitions/re...
[2] https://en.wikipedia.org/wiki/Foreign_relations_of_Taiwan#Te...
If you're launching out of Western Sahara, it strongly implies (a) you're doing something naughty and (b) procured your equipment through illicit channels. The reasoning behind (a) is you'd spend vastly more on (b) trying to do this out of Western Sahara than you ever would on compliance in an ITU-member nation. The reasoning behind (b) is export controls.
I thus presume the response would be military (i.e. detainment, not blowing things up). This would probably be the responsibility of whomever you're a citizen of, or whomever gets angry enough about you. (In Western Sahara, probably NATO, Algeria or Morocco.) The more realistic concern is someone bribing officials in an ITU member state.
There are 12 countries capable of launching satellites and technically it’s more like 10 since Iran and North Korea can’t launch anything substantial just yet.
And those two which are the closest thing you can have to a space launch capable “rogue” nation have the most interest to actually behave since they are essentially launching a ballistic missile with a small payload and if they do it without notice well some countries in their vicinity might not wait long enough to find out what it is.
Iran and North Korea are both ITU members.
Because we have international agreements in order to establish behavior that is best for all countries involved. And there would likely be diplomatic solutions presented to bring any new spacefaring nations into agreement with everyone else.