Wikipedia
An executive agreement is an agreement between the heads of government of two or more nations that has not been ratified by the legislature as treaties are ratified. Executive agreements are considered politically binding to distinguish them from treaties which are legally binding. An executive agreement is one of three mechanisms by which the United States enters into binding international agreements. They are considered treaties by some authors as the term is used under international law in that they bind both the United States and a foreign sovereign state. However, they are not considered treaties as the term is used under United States Constitutional law, because the United States Constitution's treaty procedure requires the advice and consent of two-thirds of the Senate, and these agreements are made solely by the President of the United States. Some other nations have similar provisions with regard to the ratification of treaties.
Usage examples of "executive agreement".
One reason is that NAFTA is effectively a secret -- it's an executive agreement that isn't publicly available.
Obviously that committee had to report on NAFTA, which was an executive agreement signed by the president.