An international treaty signed on February, 5, 1994, in Budapest between Ukraine, USA, Russia, and the United Kingdom concerning nuclear disarmament of Ukraine and security assurances of her independence.
According to the treaty Ukraine has abandoned her nuclear arsenal to Russia, while Russia, USA, and the UK have promised (1) to respect Ukrainian independence and sovereignty within her borders; (2) to protect Ukraine from outer aggression and not to conduct aggression toward Ukraine; (3) not to put economic pressure on Ukraine in order to influence her politics; (4) not to use nuclear arms against Ukraine."
Unlike in the case of Georgia, in Ukraine the signatories are obliged by the agreement to protect it, ironic that it might be to have to be done against one of the signatories.
The question now is: will the other signatories, USA and UK, live up to their promise? Probably not!
Bob C