All these incidents are illustrative of the particular vulnerability of CUI to the increasingly prevalent trend towards ‘grey zone’ or hybrid warfare. In this sphere, the cutting of a cable by the ‘accidental’ dragging of a merchant vessel’s anchor or a breach in a pipeline due to an unknown cause can be cloaked under the veil of plausible deniability. The resulting damage and disruption can be disproportionate to the effort involved and the direct consequences limited. It is also arguable that international maritime law has failed to keep pace with this evolving environment, with the scope for taking preventative action outside of a country’s territorial waters seemingly uncertain. In November 2025, the Helsinki District Court ruled that criminal charges against some of the crew of the vessel involved in the Estlink 2 incident could not be pursued as the case fell outside of its jurisdiction under United Nations Convention on the Law of the Sea (UNCLOS) principles.