are known as combined, coalition, bilateral, or multilateral exercises, depending on the nature of the relationship between the countries and the number of them involved. These exercises allow for better coordination between militaries and observation of enemy tactics, and serve as a visible show of strength and cooperation for the participating countries. According to a 2021 study, joint military exercises within well-defined alliances usually deter adversaries without producing a moral hazard because of the narrow scope of the alliance, while joint military exercises outside of an alliance (which are extremely rare) usually lead to conflict escalation. Exercises in the 20th and 21st centuries have often been identified by a unique code name, such as Cobra Gold, in the same manner as military contingency operations and combat operations like Operation Phantom Fury. Military exercises are sometimes used as cover for the build up to an actual invasion, as in the cases of the Warsaw Pact invasion of Czechoslovakia and the 2022 Russian invasion of Ukraine, or it can provoke opponents at peace to perceive it as such, as in the case of Able Archer 83. Types Command Post A Command Post Exercise (CPX) typically focuses on the battle readiness of staffs such as a particular Unified Combatant Command or one of its components at any level. It may run in parallel with an FTX or its equivalent, or as a stand-alone event for headquarters staff only with heavy emphasis on simulated events. Field Historical names for the field exercise, or the full-scale rehearsal of military maneuvers as practice for warfare in the military services of the British Commonwealth include "schemes," while those of the military services United States are known as Field Training Exercises (FTX), or, in the case of naval forces, Fleet Exercises (FLEETEX). In a field exercise or fleet exercise, the two sides in the simulated battle are typically called "red" (simulating the enemy forces) and "blue", to avoid naming a particular adversary. This naming convention originates with the inventors of the table-top war-game (the "Kriegsspiel"), the Prussian Georg von Reisswitz; their army wore Prussian blue, so friendly forces were depicted by the color blue. Multiple forces Several different armed forces of the same nation training together are described as having a joint exercise. Those involving forces of multiple nations are described as having a combined exercise or coalition exercise. These are called a bilateral exercise if based on