No, they never did. They were always owned and controlled by Moscow. There was no Ukrainian missile force....ever. And we did not promise to protect them. There was no alliance or treaty. Just a memorandum.
Furthermore, two other fine points. The Ukraine that signed Budapest died in the coup of 2014. The government there in Kiev is an entirely different entity that was not a participant. Agreements with Germany all died when the Nazis launched the war.
Second, the other part is that nobody (including us) would interfere in Ukraine. We threw a coup in 2014, and a war. Budapest is a dead letter by over a decade.
1. The Soviet union had no direct control of its nukes. The code system was only to authenticate communications with the local officers in charge. THEY would use physical keys. In practice it was entirely local control. Which was why the whole Soviet nuke system was a proliferation risk.
2. The said officers with the keys - many were Ukrainian.
3. A bit of adjustment would have removed the local, mechanical key controls.
4. The entire Ukrainian state remained, including the parliament, the Rada, the courts, etc. More importantly the people remain. All such agreements are ultimately with THEM.
Moscow, which is a city, never controlled any nuclear weapons, they were controlled by the USSR. When the USSR was dissolved, its nuclear weapons came into the legal possession of the USSR’s two largest constituent parts on which these weapons were located, namely Russia and Ukraine. The RSFSR may have shared a capital city with the USSR, but is was a separate legal entity and had no more right to claim ownership of nuclear weapons outside of its territory than it had to claim ownership of any other former Soviet weapons outside of its territory.