War With Russia, by General Sir Richard Shirreff (https://www.hachette.co.uk/titles/general-sir-richard-shirre...) is an excellent, prescient novel written by a NATO general, warning about an imminent war with Russia, with Latvia as the flashpoint.

Lots of highly informed, realistic speculation, and he nearly gets the year right too.

The Baltic states will never accede to Russian rule, and their guerilla tactics would eventually prevail. Just look to Winter War in Finland...

(BTW, now is the right time to retake Karelia. Are you listening, Finland?)