@jennygeddes So what Jopa said is kinda true but also a bit misleading.
To get the right answer you need to answer some questions.
Basically you want to avoid crossing the big 12%/22% tax threshold at around 80k taxable income.
Your job post military is irrelevant because these contributions directly affect your retirement income. As a Captain you make 50-80k depending on incentives and job bonuses. The question is do you plan to invest and have passive income during your retirement years specifically.
Are you married? This determines your deduction.
Are you planning on having a lot of income in retirement through investments or other passive income generation?
Your almost certainly safe putting most, if not all, of your contributions into Roth right now, but that could change depending on how much your pay increases.