The maritime ocean shipping fleet has historically been used as a logistics vehicle during the war. The United States, Britain and other countries called the merchant fleet: "fourth except land, sea and air services", the former Soviet union's merchant fleet also referred to as the "shadow" fleet by western countries. It can be seen to play a role in the outcome of war. Because of ocean transportation occupies so important, all countries in the world attaches great importance to shipping enterprise, through legislation to protect it, to foster and subsidies from the capital, to give preferential treatments in respect of cargo.