Stuart, the Russian's don't have to leave harbour to launch SLCMs that can reach the UK. Their latest conversions will allegedly carry 72 a piece. Yasens can carry 32 or 40 Kalibrs depending on which source you believe.
Yes, to counter that threat, it doesn't matter if we have 150 or 250 operational tanks. This is where I think we lack joined up thinking. We currently think we can counter Russian military aggression in the Baltics conventionally. Let's say we are right and that four Challenger tanks and five Apache helicopters we have deployed there could stop them. There is nothing to stop them going seriously assymetric on us in ways that are impossible to defend against. The alternative is to deter with analogous capabilities, but there is no political will (i.e. potential votes are lacking) to put that in place. Interestingly, the US are experimenting with treaty busting ranged conventional cruise and ballistic land-based missiles now, so it could still happen and there is a vanishingly small possibility we might deploy it. The main opposition will come from the RAF who won't want to see their expensive planes replaced by truck-launched munitions.
And how long are they going to take to arrive? If during the Cold War we had GLCM as a second strike weapon, then why would these be any different? Ineffectual though the RAF is post 2010 defence review, I find it hard to believe Russia is going to be able to unload enough SLCM's on the UK that we wont notice and wont react to. What would be the point to exclude the rest of Europe? They would have to mass produce cruise missiles to a degree the Luftwaffe did with the V1 to have the kind of strategic effects needed. Yes, in the middle of a conflict when we are already taxed, it could be an issue. As a bolt from the blue, im simply not buying it.
And yes, asymmetry is the name of the game and what im truly worried about. The ONLY good news about that is the Estonians, whom are in more threat imho than the others, have a first rate reservist system and what to my mind sounds eerily like the Volunteer movements that were so popular here in the Victorian period. I think if the Russian's ever did try to Donbas Eastern Estonia, they would be in a mess, because the Estonian light infantry would be all over them. Latvia is probably less well prepared admittedly, but they arent the Ukraine Army Circa 2014 either.
I think we want a range of capabilities of all kinds. Not JUST tanks (and im not deprecating them either) but Special Forces and ground launched drones and light infantry. Fortunately most of the allies already possess those in theatre already. At which point you have to ask, well why should we replicate capablities that already exist on the ground, why dont we do something that NATO needs and the American's seem to be slipping their gears on? And that quite clearly at this juncture is seapower. In the Baltic states, yes perhaps there is limited application of it. I somehow doubt the Russians would be as enthusiastic about territorial advancement on Ukraine or the Baltic states, with an aircraft carrier permamently off their coast. And it doesnt really matter whose flag is flying from it in this day and age. Even the Italian carrier would a JSF air wing on it would be a valid threat.
Just my view, and apologies if I am as always contentious.