This is Marco Rubio explaining how the USA promised to defend Ukraine forever if they got rid of their nuclear arsenal left after the Soviet Union fell.
Thirty years ago, on 5 December 1994, at a ceremony in Budapest, Ukraine joined Belarus and Kazakhstan in giving up their nuclear arsenals in return for security guarantees from the United States, the UK, France, China and Russia.
That is why Rubio was mortified as Trump berated Zelensky for not being grateful enough and for not accepting the U.S would not promise a security guarantee in the minerals deal with Ukraine.