UPDATE Thursday at 09:50: This story has been updated to include details of a fourth announcement of arrests by the FSB on Wednesday.

Russia’s Federal Security Service (FSB) on Wednesday made its fourth announcement in recent weeks of a large number of North Koreans detained for illegal fishing off the coast of the country’s Far East, bringing the total in recent weeks to 574 such arrests.

The FSB said Wednesday that it opened fire on the engine of a North Korean fishing vessel in order to stop the ship after it refused to comply with its “legal orders,” according to