The National Cabinet issues the general administrative regulations necessary for the execution of the national laws so far as the laws do not otherwise provide. It must secure the assent of the National Council if the execution of the national laws is assigned to the State authorities. _SECTION VI_ THE NATIONAL ADMINISTRATION ARTICLE 78 The conduct of relations with foreign countries is exclusively a function of the Commonwealth. The States, in matters subject to their jurisdiction, may conclude treaties with foreign countries; such treaties require the assent of the Commonwealth. Agreements with foreign countries regarding changes of national boundaries will be concluded by the Commonwealth with the consent of the State concerned. Changes of boundaries may be made only by authority of a national law, except in cases where a mere adjustment of the boundaries of uninhabited districts is in question. To assure the representation of interests arising from the special economic relations of individual States to foreign countries or from their proximity to foreign countries, the Commonwealth determines the requisite arrangements and measures in agreement with the States concerned. ARTICLE 79 The national defence is a function of the Commonwealth. The organization of the German People for defence will be uniformly regulated by a national law with due consideration for the peculiarities of the people of the separate States. ARTICLE 80 Colonial policy is exclusively a function of the Commonwealth. ARTICLE 81 All German merchant ships constitute a unified merchant marine. ARTICLE 82 Germany forms a customs and trade area surrounded by a common customs boundary. The customs boundary is identical with the international boundary. At the seacoast the shore of the mainland and of the islands belonging to the national territory constitutes the customs boundary. Deviations may be made for the course of the customs boundary at the ocean and at other bodies of water. Foreign territories or parts of territories may be incorporated in the customs area by international treaties or agreements. Portions of territory may be excluded from the customs area in accordance with special requirements. In the case of free ports this exclusion may be discontinued only by an amendment to the Constitution. Districts excluded from the customs area may be included within a foreign customs area by international treaties or agreements. All products of nature or industry, as well as works of art, which are subjects of free commerce within the Commonwealth, may be transported in any direction across State and municipal boundaries. Exceptions are permissible by authority of national law. ARTICLE 83 Customs duties and taxes on articles of consumption are administered by the national authorities.