The president of the United States argues that the government should impose a tariff on ball bearings because they are necessary to make various weapons, and free trade would make the United States overly dependent on foreign countries for the supply of ball bearings. In case of a war, the United States might not be able to make enough of them, and therefore would not be able to make enough weapons to defend itself.

Which of the following arguments is the president using to justify the trade restriction on ball bearings?