War reserve stock
A war reserve stock (WRS), also known as pre-paid supplies, is a collection of warfighting material held in reserve in pre-positioned storage to be used if needed in wartime. They may be located strategically depending on where it is believed they will be needed. In addition to military equipment, a war reserve stock may include raw materials that might become scarce during wartime. According to this definition, storage such as the Strategic Petroleum Reserve may be considered a war stock.
The United States maintains war reserve stocks around the world, mainly in NATO countries and in some major non-NATO allies. The US 31st Munitions Squadron is tasked with maintaining and distributing the largest war reserve stockpiles of munitions for the United States Air Forces in Europe.
Conflicts of high intensity and lengthy duration may have to rely mostly on supplies that are produced while they are ongoing. The first and second World Wars provide examples of this. But smaller wars of shorter duration where belligerents have already stockpiled sufficiently for the outbreak of conflict are able to rely on pre-existing stock. The U.S. Invasion of Grenada (1983) or Panama in 1989, in particular, were small enough to be almost wholly reliant on existing stock.