I'm confused?
Is she an illegal alien? If she is not an illegal alien, then what is the problem? Marry her if you want to marry her, but what does that have to do with a war with Russia?
Chances we will meet them on a battlefield? This isn't the 17 or 1800's. What battlefield? We are at constant war with Russia and China by proxy, but we are also contantly allied with them in other aspects. We won't ever have an all out war against Russia, and if we did, there would not be a battlefield, just a barrage of high powered, earth-killing missiles. If you are worried about being dead, then you should get married now I guess!
Hope that wasn't harsh, but your OP seems very distraught and confusing. Maybe your Russian is better than your English?

