In international relations, coercion refers to the imposition of costs by a state on other states and non-state actors to prevent them from taking an action (deterrence) or to compel them to take an action (compellence). Coercion frequently takes the form of threats or the use of limited military force. It is commonly seen as analytically distinct from persuasion (which may not necessarily involve the imposition of costs), brute force (which may not be intended to shape the adversary's behavior), or full-on war (which involves the use of full military force).

Coercion takes the form of either deterrence or compellence. Compellence has been characterized as harder to successfully implement than deterrence because of difficulties in getting actors to withdraw actions. One influential typology of coercion distinguishes between strategies to punish an adversary, raise the risk for an adversary, or deny the adversary from achieving their objectives. Successful instances of coercive diplomacy in one case may have a deterrent effect on other states, whereas a reputation for a lack of resolve may undermine general deterrence and future compellence.

Successful coercive diplomacy entails clearly communicated threats, a cost-benefit calculus, credibility, and reassurance. It frequently revolves around a demonstration of capabilities and resolve, both of which enhance the credibility of attempts to coerce others. Scholars have identified several factors as contributing to successful coercion, such as power, interests, reputation, credibility, resolve, and ability to signal.

Daniel Byman and Matthew Waxman define coercion as "getting the adversary to act a certain way via anything short of brute force; the adversary must still have the capacity of organized violence but choose not to exercise it". Coercion strategy "relies on the threat of future military force to influence an adversary's decision making but may also include limited uses of actual force".

Robert Pape uses the term coercion as a synonym for compellence.

Thomas Schelling and Robert Pape distinguished between coercive strategies that sought to:

Pape also added the strategy of decapitation, which typically entails targeting leaders. Alexander Downes and Kathryn McNabb Cochran distinguish between two punishment strategies: (i) Coercive victimization (which raises the costs of war for a government by targeting its civilians) and (ii) Eliminationist victimization (which removes civilians from territory).

According to Richard Ned Lebow, successful coercion tends to involve: