atm in alpha 3, it's 50% of either side in a 1v1 war having the advantage, and for the invaded by all event it is 100% of the invaded having a dissadvantage, but a 1 in 6 chance of it being a "controversial politician" event and therefore the one being invaded having the advantage, also during the events who got advantage do slightly change so it gives the overall advantage to the bigger countries as it takes longer time to invade and therefore have more time for the advantage to flip