The POHA has "extraterritorial" reach in certain circumstances. Generally, the court has extra-territorial jurisdiction if the victim was in Singapore at the time of the harassment and the harasser knew or had reason to believe that the victim was in Singapore, or if the harasser was in Singapore at the time of the harassment even if the victim was overseas.

For more information, you may refer to https://www.judiciary.gov.sg/civil/cases-eligible-protection-from-harassment