Since World War II, formal declarations of war have been rare, especially actions conducted by developed nations in connection with the Cold War. Rather, nations involved in military conflict (especially the major-power nations) sometimes describe the conflict by fighting the war under the auspices of a "police action" to show that it is a limited military operation different from total war.
The earliest appearance of the phrase was in 1883, referring to attempts by Netherlands forces and English forces to liberate the 28-man crew of the SS Nisero, who were held hostage. The Dutch term politionele acties (police actions) was used for this. It was also used to imply a formal claim of sovereignty by colonial powers, such as in the military actions of the Netherlands, United Kingdom, and other allies during the Indonesian National Revolution (1945–1949) and the Malayan Emergency (1948–1960).
The two major Dutch military offensives, of July 1947 and December 1948, during the Indonesian National Revolution were referred to by the Dutch government as the first and second "police actions". The 1948 invasion, by India, of Hyderabad State, code named Operation Polo, was referred to as a police action by the government.
The Soviet war in Afghanistan was an undeclared war and hence also could be described as a police action, especially since the initial troop deployments into Afghanistan were at the request of the Afghan government.
In other events, the Congress (of the United States) had not made a formal declaration of war, yet the President, as the commander-in-chief, has claimed authority to send in the armed forces when he deemed necessary, with or without the approval of Congress. The legal legitimacy of each of these actions was based upon declarations such as the Gulf of Tonkin Resolution and Iraq Resolution by Congress and various United Nations resolutions. Nonetheless, Congressional approval has been asserted by means of funding appropriations or other authorizations as well as the contested War Powers Resolution.
Police actions are authorized specifically by the Security Council under Article 53 (for regional action) or Article 42 (for global action).
Use of the term does not appear to have gained currency outside of the limited arena of justification of military action: for example, the U.S. Navy refers to the Korean conflict as the Korean War, and when they refer to police action, they surround the term in quotation marks.[improper synthesis?]
Similarly, a plaque at the Vietnam Veterans Memorial refers to the Vietnam Conflict as a war, not a police action, even though it was undeclared.
Use of the term "police action" is intended to imply either a claim of formal sovereignty or of authority to intervene militarily at a nation's own discretion, typically unilaterally or with a small group of nations. This is often done through the United Nations or by asserting that the military operation is defensive or humanitarian in nature such as the United Nations Stabilisation Mission in Haiti or the Invasion of Grenada.
Veterans often display a high degree of disdain for the term "police action", as it somehow implies that their sacrifices were not legitimate and perhaps also that they are not even veterans of a true "war".