Comment Nuclear "surety" (Score 1) 267
The main impediment to the strategic force upgrade is a process called "nuclear surety". It's what you think it is: a very comprehensive testing process to ensure that the system can't be accidentally triggered (missiles launched.) Surety is as comprehensive as it can be conceived, which means that no process is ever perfect, but this one has a lot of history behind it such that the probability of an accidental or forced launch is very, very low.
Surety costs significant money, about 65-80% of the cost of upgrading the system. Add to that the general cautiousness of changing the system in any way, and you get the "Holy Cow! You're still using 1960's technology?"