Bulungan, North Kalimantan. Four policemen, including a mid-ranking officer heading an anti-narcotics unit, have been arrested on suspicion of involvement in a cross-border drug syndicate operating near the Indonesian-Malaysian border, authorities said on Thursday.

The suspects, all members of the Nunukan District Police in North Kalimantan, were detained on Wednesday by a joint team from the provincial police and the National Police while traveling to Sebatik Island, a known border hotspot.

“We apply a zero-tolerance policy in combating drug trafficking -- regardless of rank or position, anyone involved will be held accountable under the law,” said North Kalimantan Police Chief Inspector General Hary Sudwijanto during a press conference at provincial police headquarters in Bulungan Regency.

Hary declined to provide further details regarding the case or the evidence leading to the arrests, citing the ongoing investigation. The identities of the four suspects have also not been disclosed.

The arrested officers are expected to be transferred to the National Police headquarters in Jakarta for further investigation.

“One of the suspects is the head of Nunukan Police’s anti-narcotics unit. We are expanding the investigation, but for now, four suspects have been taken into custody,” Hary added.

The operation has drawn significant public attention due to Nunukan’s strategic location along the border with Malaysia -- a region widely considered vulnerable to drug trafficking involving syndicates from both countries.

Nunukan also serves as a major transit point for Indonesian migrant workers heading to Malaysia and for undocumented workers deported by Malaysian authorities, further complicating border control efforts.