Speaking about the occasion, Susi Pudjiastuti, the fisheries minister, noted that illegal fishing ships are threatening the local fishing industry. He explained that their operators are frequently perpetrators of modern day slavery.
In this year's events, the operation was conducted more quietly than in other cases, when the ships were blown to pieces.
Indonesia claims it has sunk over 500 illegal fishing vessels since October 2014, many with explosives.
During 2018, the ministry sunk 125 mostly foreign vessels, including 86 Vietnamese-flagged ships, 20 Malaysian and 14 from the Philippines.
As Indonesia claims a big exclusive economic zone, it is often penetrated by foreign fishing vessels. What is more, a week before Indonesia sank the ships, an Indonesian navy patrol ship was rammed by two Vietnamese coast guard ships.
This came after the Indonesian ship intercepted a boat on the grounds that it was fishing illegally in its waters. On the other hand, Vietnam claimed that the area was Vietnamese waters.
Indonesia ended up detaining 12 Vietnamese fishermen from the boat, which was included in the boats that sank, sources reported.