True, there is an implicit threat of violence when parties interact at that level. But there is also a hope on both sides that if all the rules are followed, violence will not be necessary even if one party gets the better of the other. E.g., the central banks of unfriendly nations transact with one another according to international norms and rules, even though either side could escalate to "kinetic" reprisals. The force of norms and rules is strongest between parties with balanced power (otherwise the stronger side can just pull a Commodore Perry like you say).