And it's a far more insidious form of warfare. Since there's no physical invasion the target country can't complain that it's being threatened. I remember North Korea even printed counterfeit dollars in it's hidden war with America. Not just destroying the economy but also funding various activist groups to sow chaos and division in the country.
I'd also include the access to rivers in this one, like Turkey damming the Tigris and Euphrates and China damming the Mekong. With the latter, they've caused damage whenever they would release water without warning. You can basically hold the downstream countries hostage, whether you restrict flow or just let out the water, it's not going to be good for them.
War is not necessarily carrying guns and missiles ,these days wars are been fought with wisdom not with bombs and riffles, there something we call economic war ,Ban and sanction like we experience all nations against russia not necessarily done violently but with wisdom to affect it economy ,once money is not in circulation again it will lead to protest by his people against his government for dissatisfaction.
There is also another way which is something called Bio war.
It maybe the part of human evolution, we used to fight with bow and arrow then knife and then guns and tanks now the next stage of the evolution but the main intention is crush the economy of opposition and take over the control for that people can go to any extreme.
Humans were pretty much the best ranged units in the meta and progressed from stone fling to drones LOL.
