Wikileaks and Obama. An Impeachable Offense?

I'm no expert on hacking and cyber warfare but it seems to me that, after the first and second Wikileaks releases of top secret information, the White House would have come up with a plan for stopping additional leaks like the very harmful one that occurred this past week. The question should be asked why a hacker named "The Jester" can shut down Wikileaks' website for several hours on Sunday, but our Cyber Command could not? Did the president give the order to do everything necessary to block the release of this information and the efforts failed, or was the order never given? If the order was not given, and the president did not do everything in his power to stop this leak, should the president be held accountable for the damage caused? If you think he should be held accountable, do you think this is an impeachable offense?