Juppie902,
The Budapest agreement was signed by the UK and USA and - to a lesser degree - France, but not NATO.
It provides security assurances, such as going to the UNSC if their territorial integrity is threatened, but it does
not impose any a legal obligations of military assistance - and hasn’t proved of any great value so far.
The Baltic states joined NATO and have allied tripwire forces based on their territory, yet still are considered vulnerable. Ukraine? Don’t hold your breath....