As I said in my earlier reply, it is remarkably easy for the world community, and as Flash noted, civilian or amateur satellite observers, to confirm that nothing is in orbit.
The fact is that even if the rocket carried a satellite payload that was intended to deploy to orbit (something I personally consider highly unlikely), the launch itself is still a "success" for DPRK...they were able to do what they wanted to do, without the intervention of any other power. Granted, Japan and/or the US may have taken action were there any actual threat, but this is still a propaganda win even if it was a dismal technical failure...and at that, it is at least a partial success because the first stage got off.
Not that any of this matters, since DPRK and its state establishment got its wishes, in complete defiance of UNSEC 1718 (2006). With PRC urging "restraint" on all sides, it will be interesting to see what the Security Council is able to come up with in response. Personally, I would have hoped for a more "successful" launch with an equally "successful" disabling of the rocket and/or its payload by US forces. But to what end? DPRK would still have the same propaganda, perhaps interspersed with accusations of "sabotage" by the US.