Which country are you in? The phrase "military retirement", used as in your post, suggests to me that you might be in the USA. This website is UK-based and our laws and legal structures here are
very different to those in the USA, so (if my guess at your location is correct) we might not be the best people to ask. You might fare better on Quora
https://legaladvice.quora.com/
or Stack Exchange
https://law.stackexchange.com/
(If you are in the USA, and going to post on one of those sites, I suggest mentioning which state you're in as the situation might vary across different states).
Sticking with my guess that you're in the USA, this might possibly be relevant:
https://www.dummies.com/relationships/divorce/making-changes-to-your-divorce-agreement
If I've got it wrong though, and you're actually here in the UK, this will go some way to answering your question:
https://www.divorcesolicitors.com/can-a-divorce-settlement-be-reopened/