Russian (or Polish?) military abbreviation?

[MacGyver]

Hi,

FI have a letter to my Grandfather, and I believe the beginning says something about his military rank. I thought the letter was in Polish, but now that I'm looking at some Russian words, I'm beginning to think it's probably Russian. Anyway, the letter is Russian/Polish, but he served in the USA military in WW1. The beginning of the letter says something like this:

Kusovry Pumo, M.S.A ___!!!

The blank is my ancestors name. Is M.S.A a military abbreviation? A was his first initial (or so we've been told...), so it might just be M.S. I have no idea. Does this ring a bell for anyone? It may or may not be military, but I don't know what else it would be. I can't figure out what it says before, so the kusovry stuff is probably not right. I can't make out any real letters from it.

Thanks,

Mac