The President of the United States and the king of a foreign nation entered into a treaty agreeing that citizens of the foreign nation who reside in the United States would not be taxed by the United States and that United States citizens who reside in the foreign nation would not be taxed by it. The treaty was ratified by the United States Senate and the royal council of the foreign nation. One year after the treaty became effective, the foreign nation began to tax United States citizens within its borders. The President immediately declared the tax treaty to be void and ordered the Internal Revenue Service to tax citizens of the foreign nation living in the United States. Is the President's action constitutional?