You should re-evaluate how you acquire information and which sources do you trust. You could have found out that this is not true by spending 10 seconds looking it up. Ukraine had nukes, but gave them back to Russia due to US and Russian influence.
How many other things do you believe that are flatly not true?
Regarding your next statement, Russia is not interfering in what is happening in Ukraine AT ALL. As opposed to EU and US who send their emissaries to Ukraine very often. The only "interference" from Russia is giving to Ukraine a huge credit and pushing down the gas prices which I guess is more help than interference. Also, this is not about Putin or anybody else. Most of Ukraine is culturally and historically extremely close to Russia. They are pretty much the same people. This may not be true regarding a couple of the most Western regions of the country. Those guys, I believe, have their full right on "independence" but that effectively would mean the split of the country which is the hardest thing to do.
Please be careful with selectively picked information. It's not constructive and not helpful.
Ukraine gave up on its nukes in nineties in exchange for military guarantees from US, NATO and Russia. No warheads, no enriched uranium (has been given away by the current president in exchange of nice handshakes with US at the beginning of his term).
Russian leaders are trying to restore its Soviet era, where Ukraine used to be the second most populated country after Russia itself. Clearly, this is a big deal for them. Location wise is not that important, all Baltic countries are way closer to Moscow.
I read on Stratfor that Russia does not want Ukraine to become independent because it's basically the "soft underbelly" leading into Russia. It's basically the equivalent of letting Texas become independent. With Putin in control, there's no way he's letting Ukraine go free, especially given all the nukes, its strategic location, etc.