You are correct your military pension is not taxed in UT. When entering your 1099-R in the federal "Deductions and Credits" section you will have follow on question that asks if your 1099-R was for a "Military Pension" you will need to select that button. The page after that you should select "Non-Qualified" for a military pension. Finish the section interview.
This will exclude the military retirement 1099-R from UT taxable income.