A cable between Sweden and Finland that provides crucial power transmission between the two countries experienced an unexpected outage, going offline for several hours on Tuesday morning.

Fingrid, Finland’s national grid operator, said the high-voltage power cable appeared to be unharmed despite the disruption.

The outage affected Fenno-Skan 2, an 800-megawatt (MW) high-voltage submarine cable linking the two countries.

Fingrid said the disruption was caused by a malfunction at a substation rather than anything malicious.

The Baltic Sea region has been a focus of concern in recent years following Russia’s invasion of Ukraine.