Reminds me of WW2 battleships. Claimed to be unsinkable from air attack.
After the Price of Wales and Repulse, they stayed in port because they were too expensive to risk.
They sank the Moskva, which would be expensive to replace (which I doubt they will) but it had no strategic effect on the battle field.
Also, there's a whole bunch of battleships that *didn't* stay in port after the sinking of Force Z. There's one that fought her way across the entire planet, both major theaters of WW2, sitting in dry dock in Galveston right now.
I think you need to review your WW2 history.