A show of force is a military operation intended to warn (such as a warning shot) or to intimidate an opponent by showcasing a capability or will to act if one is provoked. Shows of force may also be executed by police forces and other armed, non-military groups.
Shows of force have historically been undertaken mostly by a military actor unwilling to engage in all-out hostilities, but fearing to 'lose face' (to appear weak). By performing a carefully-calculated provocation, the opponent is to be shown that violent confrontation remains an option, and there will be no backing off on the principle that the show of force is to defend.
Shows of force may be actual military operations, but in times of official peace, they may also be limited to military exercises.
Shows of force also work on a smaller scale: military forces on a tactical level using mock attacks to deter potential opponents, especially when a real attack on suspected (but unconfirmed) enemies might harm civilians. As an example, most air "attacks" during Operation Enduring Freedom and Operation Iraqi Freedom have been simple shows of force with jet aircraft droppping flares only while making loud, low-level passes. One recent 12-month report for Afghanistan noted 18,019 strike sorties by US military aircraft, with weapons use for only 3,330 of the missions.
Shows of force, while intended as 'gestures', might considered part of a larger or more extensive operation, and they can invite responses or retaliation beyond those intended.