+1. I used to run HR for a mid-sized company and was involved in our Healthcare negotiations. Typically, an HSA is tied to taking one of the company's medical plan options and is most often tied to a high-deductible, low premium option. An FSA may or may not be offered by the company medical plan but is an independent structure typically administered by a benefits provider vice a health care provider (HMO, etc.).
In my experience, you could not get an HSA unless you used the company's medical plan (doesn't mean you can't have TRICARE as well, but you need to be paying the company medical plan premium in order to qualify for the HSA). An FSA (if offered) doesn't require that, it is simply a pre-tax payroll deduction deposited into the FSA for your use...