Possessing a credible threat of military force tends to undermine the effectiveness of diplomacy.

The idea that possessing a credible threat of military force undermines the effectiveness of diplomacy is not universally true. In many instances, having a credible military threat can actually strengthen a nation's diplomatic position by adding weight and urgency to negotiations. When one party knows that the other has military capabilities and is willing to use them if necessary, it can lead to more serious considerations during diplomatic discussions. This credible threat can serve as a deterrent against adversarial actions and influence the behavior of other states.

Furthermore, in international relations, the balance of power and the presence of military strength can play significant roles in diplomatic outcomes. For example, a nation may leverage its military capabilities to secure concessions or ensure compliance in negotiations, which does not inherently undermine diplomacy but can enhance the effectiveness of diplomatic efforts.

In contrast, the notion that threats always undermine diplomacy overlooks the complexity of global interactions and the varied contexts in which diplomacy occurs. There are situations where the presence of military force is a critical element of negotiations, leading to successful outcomes rather than detracting from diplomatic efforts.