Same thing is true for Japan. Everything seems fine for a while, and suddenly the numbers explode.
South Korea is still testing aggressively. Recently they even started re-testing recovered patients. Those who tested positive had their contacts traced and tested too. As long as they remain vigilant, they will not see another big explosion. They seem to have the right attitude.
I’m waiting to see if there will be a little outbreak as a result of the elections they held recently.
A lot of people were perplexed by Japan's lack of testing. Seems like Japan's strategy (whatever it was) didn't work out in the end.
[1] https://en.wikipedia.org/w/index.php?title=Template:COVID-19...