World News

People in Western states are mostly docile. Occupied Korea has been wracked with strikes and protests for the past 2 years. But probably the biggest reason this martial law was declared is that the opposition parties have been trying to get Yoon and his associates investigated for multiple corruption scandals for the last 2 years. They also hold a parliamentary majority and are blocking everything he tries to do. It's likely they actually approached something that could incriminate him, or they refused to vote for something they should have, so now Yoon is acting to regain authority over the government (since calling everyone that disagrees with him a communist, spy or traitor, doesn't really seem to work).