We would need a LOT of new international guidelines for this.

It’s not clear to me where we would draw the line, since there’s not really an enforceable difference between, “Allowing you to use our financial system is causing us harm, so you can’t do that anymore,” and “You can’t use our financial system until you <insert demands here>.”

While a blockade is recognized as an act of war, an embargo is not. The US sanctions usually operate like a specific, services-based embargo, so there’s no interpretation of CURRENT international law rendering it an act of war. Again, we would need new guidelines to meet your goal.

I think shared ownership goes against human nature

I think the vast majority of things are shared. Air, water, soil… roads, schools… your education… the bathrooms at the supermarket… the murals/sculptures that make your town look less like a shithole…

It’s perfectly in line with human nature, actually, to share things. People who amass hoards of wealth and fight for power and control… those are the weirdos.