Tariff
A tariff is a tax on imports or exports between sovereign states. It is a form of regulation of foreign trade. It is a policy that taxes foreign products to encourage or protect domestic industry. It helps limit trade deficits. The tariff is historically used to protect infant industries and to allow import substitution industrialization.
Customs war
A Customs war, also known as a "toll war" or "tariff war", is a type of economic conflict between two or more states. In order to pressure one of the states, the other raises taxes or tariffs for some of the products of that state. As a reprisal, the latter state may also increase the tariffs.