They were never given security guarantees, they were given security assurances, which is kind of the issue that led to this. Granted all geopolitics is down to the whims of leaders upholding agreements, but on paper a security guarantee is near automatic cobeligeration with the defending party while a security assurance is in no way as heavy handed. I would say that the Ukrainian goal is to have an agreement that will give them dependable allies in a future conflict.