the entire point of an SSBN fleet is that no one knows where they are
(consider the UK's "triad": they have no more air, no more land, and their seaborne missiles come from the US, but at least their boomers are from Cumbria, so they still have a permanent seat on the Security Council)
If you're curious as to how one might go about looking for subs, https://www.wassenaar.org is not a bad place to start.
Anyone know what he’s referring to here about submarines?