Ultimatum

English diplomacy has devised the adroit reservation that refusal will be regarded as an "unfriendly act", a phrase which serves as a warning that the consequences of the rupture of negotiations will be considered from the point of view of forcing a settlement.

This opens up a variety of possibilities, such as good offices, mediation, the appointment of a commission of inquiry, arbitration, reprisals, pacific blockade and war.

[a] Unlike the circumstances of an ultimatum, the scenario of deterrence is not bound by specific constraints of time, place, or action, and though a threat may be present, there is no formal guarantee of it being acted out.

The scenario of nuclear deterrence (particularly the United States and the Soviet Union in the Cold War) is a good example of this concept: while both nations maintained a sizeable stockpile of nuclear weapons aimed at each other, the intent was to prevent open conflict (closed loop), and that no formal condition for initiating conflict was ever established, except in retaliation for the other side initiating an attack.

In an ultimatum situation, such as during the Cuban Missile Crisis, either nation would threaten the use of nuclear weapons if certain demands/constraints were not met independent of that retaliatory capability that would have a fixed point of no return—compliance or warfare.

[8] The strategy behind an ultimatum and coercive diplomacy is that, when faced with significant pressure and a looming threat, the opposing actor will be compelled to make concessions due to the sense of urgency.