This section is from the book "Constitutional Law In The United States", by Emlin McClain. Also available from Amazon: Constitutional Law in the United States.
The states can have no relations whatever with foreign governments (Const. Art. I, § 10, ¶ 1). Toward foreign powers, the United States collectively constitute one single power, represented by the federal government, and the relations between that government and foreign governments are through the executive department and in the name of the president as chief executive. Congress cannot deal with foreign powers, and the courts can only take cognizance of their existence and rights by recognizing, interpreting, and applying the action of the executive department, evidenced by treaties or otherwise. The action of the executive department in determining in a controversy with a foreign government whether certain territory is territory of the United States cannot be interfered with by the courts. (See Jones v. United States.) So also it is for the executive department to determine whether this government will recognize as an independent sovereign power a foreign state claiming such recognition. In short, the entire diplomatic relations between this and other countries are under the control of the executive; and the action of the executive in such matters is binding upon Congress, the courts, and all federal and state officers.
 
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