It's not quite that simple. The wording (at least in English) was very carefully ambiguous, promising "assistance" if something happens but not quite a security guarantee, but it kind of sounds like a security guarantee.

https://en.wikipedia.org/wiki/Budapest_Memorandum

Another key point was that U.S. State Department lawyers made a distinction between "security guarantee" and "security assurance", referring to the security guarantees that were desired by Ukraine in exchange for non-proliferation. "Security guarantee" would have implied the use of military force in assisting its non-nuclear parties attacked by an aggressor (such as Article 5 of the North Atlantic Treaty for NATO members), while "security assurance" would simply specify the non-violation of these parties' territorial integrity. In the end, a statement was read into the negotiation record that the (according to the U.S. lawyers) lesser sense of the English word "assurance" would be the sole implied translation for all appearances of both terms in all three language versions of the statement.[18] In the Ukrainian and Russian version of the document, the wording "security guarantees" was used though.[20][21]

#justclintonthings