Hi Nan D., that's one of the first things I looked at when I started considering staying in the UK. And being a NV resident, I won't be liable for any state income tax!
There is a provision in US law that prohibits any one state from taxing the income of a pension from sources in another state. So, unless you maintained your Nevada residency, you wouldn't be taxed there on your pension even if they did have state income tax.
Effective for retirement income received after December 31, 1995, federal law prohibits any state from taxing certain retirement income (mainly pension income) unless you are resident of, or domiciled in, that state.
I don't think you'll get social security (I don't believe you had to contribute?), but if you did, it would only be taxable in the UK. The personal allowance for someone living in the UK on UK taxes is, I think, £11,850. You'd only pay UK taxes on any social security above that amount. You would not pay any taxes on your social security to the IRS.
Caveat to the military pension not being taxed in the UK. I think if you become a citizen, it becomes taxable here.