Try as they might, police in Thailand can’t seem to eradicate their country’s infestation of South Korean ex-pats running illegal online gambling sites.

Thailand police have been run ragged attempting to stamp out the hordes of South Korean nationals who decided to spend 2015 in sunny Thailand taking online sports and casino wagers from their countrymen back home. The common justification cited by most of those arrested has been the comparatively lenient punishment that Thai authorities mete out for illegal gambling offenses.

Last week, police and immigration authorities swooped down on three separate residences in Pattaya, arresting 11 South Korean nationals in the process. The three operations, all located in rented luxury houses (one with an indoor swimming pool), were all connected to the same online gambling network.

One operation reportedly handled wagers worth 11m baht (US $316k) in the previous month, while another handled 800k baht ($23k) on the day preceding the raids. In total, police seized 20 computers used for taking wagers.