European officials are investigating unexplained leaks in the Nord Stream 1 and 2 pipelines that bring natural gas from Russia to Europe under the Baltic Sea and on Wednesday vowed retaliation if the leaks are the result of sabotage.

“All available information indicates those leaks are the result of a deliberate act,” European Union foreign policy chief Josep Borrell said in a statement on behalf of the bloc’s 27 members, according to the Associated Press. “Any deliberate disruption of European energy infrastructure is utterly unacceptable and will be met with a robust and united response.”