Calculating the power of a fleet is a daunting and imprecise task. In the Washington Naval Treaty, tonnage and gun caliber were used as metrics to set the ratio of capital ships between leading world navies. Capital ships were seen as the supreme arbiters of a naval conflict. The London Naval Treaty established similar rules for tonnage and gun caliber for smaller combatants. The United States Navy counts battle force ships, which includes combat logistics forces, toward its end strength.