CNN — Investigators are trying to crack the mystery of how two undersea internet cables in the Baltic Sea were cut within hours of each other, with European officials saying they believe the disruption was an act of sabotage and US officials suggesting it was likely an accident. But two US officials familiar with the initial assessment of the incident told CNN on Tuesday the damage was not believed to be deliberate activity by Russia or any other nation. Instead, the two officials told CNN they believed it likely caused by an anchor drag from a passing vessel. Such accidents have happened in the past, although not in a quick succession like the two on Sunday and Monday.