Did the Russians hack JP Morgan, and how can they be stopped if they did?

So, a bunch of US financial institutes have been hacked. Nothing new there, if we are being brutally honest. The newsworthyness in this particular case comes courtesy of one of those organisations apparently being none other than JP Morgan Chase. USA Today reported yesterday that a federal law enforcement official had told the media outlet, unofficially, that Russian hackers were behind the series of breaches which resulted in the loss of "sensitive data." JP Morgan Chase did not confirmed the accuracy of the report, but a spokesperson did tell USA Today that it uses "multiple layers of defense to counteract any threats" and "constantly monitor fraud levels." Which is about as helpful as a bucket of mud to clean the floor with. The FBI were a little more forthcoming, admitting that it is working with the secret service in order to determine the scope of "cyber attacks against several American financial institutions." So what do we know about what happened? The answer, as you might have expected by now, is very little. That hasn't stopped the security industry from lining up to provide DaniWeb with some guesses though.