Nation A gets kidnapped by Nation B, straighforwards right? Only Nation B has already kidnapped A's sibling/twin (C), and the reason why this is a problem is that what you do to A, c feels and vice versa. In essence if you wanted to torture A but not leave a mark, you torture C - whatever C feels, A feels as well, but without the marks.

Kinda Quirky Bonus: It's not physical torture that B uses, but sex.
Even more weirder bonus: It's a consensual relationship between the three, because really if C feels eevveerrrything, then A'd be aware then C got sex-napped.