hostage

(hŏsˈtĭj)

1. A person held by one party in a conflict as security that specified terms will be met by the opposing party.
2. One that serves as security against an implied threat: superpowers held hostage to each other by their nuclear arsenals.
3. One that is manipulated by the demands of another: “National policies cannot be made hostage to another country” (Alan D. Romberg).