A memorandum is a piece of paper that lacks the force of a treaty.

The Budapest Memorandum was not ratified by the U.S. Senate. It is a political agreement rather than a legally binding treaty, which means it did not require Senate ratification. The memorandum was designed to provide security assurances to Ukraine, Belarus, and Kazakhstan in exchange for their accession to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) as non-nuclear states. The U.S. administrations involved did not seek Senate ratification because they believed the Senate would not approve a treaty with military commitments to Ukraine. Instead, the memorandum was adopted with more limited terms as a political commitment rather than a formal treaty[1][4][5].

Sources [1] Budapest Memorandum - Wikipedia https://en.wikipedia.org/wiki/Budapest_Memorandum [2] Ukraine: The Budapest Memorandum of 1994 https://policymemos.hks.harvard.edu/links/ukraine-budapest-memorandum-1994 [3] Budapest Memorandum at 25: Between Past and Future https://www.hks.harvard.edu/publications/budapest-memorandum-25-between-past-and-future [4] What the Budapest Memorandum means for the U.S. on Ukraine https://www.washingtonpost.com/politics/2022/02/01/what-budapest-memorandum-means-us-ukraine/ [5] Constructive Ambiguity of the Budapest Memorandum at 28 - Lawfare https://www.lawfaremedia.org/article/constructive-ambiguity-of-the-budapest-memorandum-at-28-making-sense-of-the-controversial-agreement [6] Ukraine war: what is the Budapest Memorandum and why has Russia’s invasion torn it up? https://theconversation.com/ukraine-war-what-is-the-budapest-memorandum-and-why-has-russias-invasion-torn-it-up-178184 [7] Memorandum on security assurances - UNTC https://treaties.un.org/Pages/showDetails.aspx?objid=0800000280401fbb [8] [PDF] Ukraine's Territorial Integrity and the Budapest Memorandum https://www.wilsoncenter.org/sites/default/files/media/documents/publication/Issue%20Brief%20No%203--The%20Breach--Final4.pdf