Whenever, during the existence of a war in which the United States is not engaged, the President shall be satisfied that there is reasonable ground to believe that under the laws, regulations, or practices of any country, colony, or dependency contrary to the law and practice of nations, the importation into their own or any other country, dependency, or colony of any article the product of the soil or industry of the United States and not injurious to health or morals is prevented or restricted the President is authorized and empowered to prohibit or restrict during the period such prohibition or restriction is in force, the importation into the United States of similar or other articles, products of such country, dependency, or colony as in his opinion the public interest may require; and in such case he shall make proclamation stating the article or articles which are prohibited from importation into the United States; and any person or persons who shall import, or attempt or conspire to import, or be concerned in importing, such article or articles, into the United States contrary to the prohibition in such proclamation, shall be liable to a fine of not less than $2,000 nor more than $50,000, or to imprisonment not to exceed two years, or both, in the discretion of the court. The President may change, modify, revoke, or renew such proclamation in his discretion.