Being a foreigner and all, I’ll forgive you for not knowing how our system works. None of those “memoranda” or “agreements” were ever ratified by the US Senate. They aren’t worth a warm bucket of p***. On top of that, the Budapest thing is a bill Clinton promise, even more worthless than that bucket of p***.
The President can enter the United States into an international agreement with other countries without asking the Senate to approve anything. But the agreement is considered an executive agreement and is not officially a treaty. But the terms in an executive agreement can still be binding between the two parties under international law.
There is also a precedent:
United States v. Pink (1942) states that an executive agreement can hold the same legal status as a treaty.
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The U.S. Supreme Court, in United States v. Pink (1942), held that international executive agreements validly made have the same legal status as treaties and did not require Senate approval. In Reid v. Covert (1957), while reaffirming the president’s ability to enter into executive agreements, the court also held that such agreements cannot contradict existing federal law or the Constitution.