True, I think that from now on, countries will hold on to their nukes like there's no tomorrow.
Also, back when the treaty was signed, I think the president in Ukraine was Leonid Kuchma. I am thinking how would this person - along with the politicians representing the country - not ask for more stipulated paragraphs about military aid. You'd think that having a border with Russia would prompt you to maybe think at the possibility that - who knows - someday maybe Russia would want to bully again. That nuclear arsenal that Ukraine had was more than a few aces under the sleeve. But, what's done is done, that's life.
Now, I think Putin wants to take Ukraine, as in he's not interested in anything less than total surrender of the current government, that is the big problem. Remember, Putin is a violent person, ex-KGB and that is a huge factor in his decison-making and thought-process. I think like in any battle/war, you have to take the decision if you want to fight until the very end or not, if Ukraine being part of Russia, is worse than death for the people in Ukraine, because if it's not, then a lot of blood can be spared. I don't know, it's really a bad spot and such a huge/heavy responsibility on Poroshenko's back. I wholeheartedly hope for the best for the Ukrainian people.