A Chinese commercial vessel that has been surrounded by European warships in international waters for a week is central to an investigation of suspected sabotage that threatens to test the limits of maritime law—and heighten tensions between Beijing and European capitals.

Western officials believe that Moscow likely orchestrated the Baltic Sea incident as part of growing efforts to cripple key maritime infrastructure.

European investigators believe that a Chinese commercial ship purposefully dragged its anchor in order to slash through two critical data cables.

Sweden has demanded that the Chinese vessel connected to an investigation of two Internet cables in the Baltic Sea being damaged earlier this month return to its waters as part of the probe.

Sweden’s prime minister has urged a Chinese ship linked to the cutting of two cables to move into Swedish waters, as the country steps up its investigation of the potential incident of sabotage in the Baltic Sea.