> ...the Department of the Interior settled on a single justification for blocking turbine installation: a classified national security risk.

To speculate on what this risk is, the two obvious risk I can think of would be:

- Susceptibility to seabed warfare[0]. A rival nation can sabotage the infrastructure and maintain deniability, like we have seen with the Nord Stream sabotage[1].

- Potential interference with passive sonar systems, the turbines are likely to generate a fair bit of noise, which could potentially make it harder for SOSUS[2] to detect rival submarines.

[0]: https://en.wikipedia.org/wiki/Seabed_warfare

[1]: https://en.wikipedia.org/wiki/Nord_Stream_pipelines_sabotage

[2]: https://en.wikipedia.org/wiki/SOSUS

If the latter were true, the permits would have never been granted. The permits took years of back and forth, public and government commentary.

The former is a threat vector but one that can be priced into the ongoing maintenance costs.