I’m banking, in the present climate, on the last two sentences reference the business case.
If you need SSBN to keep one in station, yo7 need at least 4 to keep one AEW in the air - and with servicing schedules and snags that’s with luck.
One in deep service, one in routine maintenance you can’t maintain one airborne. You might manage to rotate 2, but one snag and you’re back to one - with transit times as well as TOT issues.