I'm reasonably sure VLF and ELF are very much in use but it seems as though ELF was abandoned by the US Navy. The Navy does continue to use VLF though. https:/

I'm reasonably sure VLF and ELF are very much in use but it seems as though ELF was abandoned by the US Navy. The Navy does continue to use VLF though. https://www.thedrive.com/the-war-zone/25728/chinas-new-york-city-sized-earthquake-warning-system-sounds-more-like-way-to-talk-to-subs https://www.thedrive.com/the-war-zone/25728/chinas-new-york-... http://www.nukeresister.org/static/nr135/135elfcloses.html http://www.nukeresister.org/static/nr135/135elfcloses.html