This is not a "Bucharest Memorandum", but a memorandum of a convo between Bush and Putin, which happened on April 6th of 2008. What you are talking about is from [0], and you should not believe Putin's words verbatim. Remember: he likes to "teach" history people from other side of the world. He cherrypicks some facts, omits other facts, distorts some other, and spits out some narrative to base his claims on it. Later these narratives get to school history books and become the history as russians know it. This practice is more than hundred years old by now in USSR and later Russia.

[0] https://nsarchive.gwu.edu/document/33711-document-3-memorand... page 5