A primary measure of a nation's power projection is its over-the-beach capability (OTB). This consists of the number of soldiers, tanks, vehicles, and helicopters that a nation can stage over an adversary's defended coast in a time of war. Generally, these elements only count if they can be projected across hundreds of kilometers of open ocean. Over-the-beach capability determines a nation's power projection together with forward airpower (strength of aircraft carriers and/or overseas airbases), alliances, and nuclear options.