Depending on the nature of the conflict, it might not be possible at all. Countries generally reserve the right to control both what crosses and happens within

Depending on the nature of the conflict, it might not be possible at all. Countries generally reserve the right to control both what crosses and happens within their borders- that’s more or less the definiton of sovereignty. If two countries have mutually-exclusive regulations regarding some goods, there isn’t a legal trade in those goods between them.