There was an item on BBC1 several weeks ago on Sunday morning 7-8.00 o' clock ish, where they go through the most viewed U Tube clips, one of these clips taken from a weather satalite showed what they discribed as a vapour trail starting over California tracking over Pacific towards Japan very near to asian northern hot spot of the moment, then turning back to nearly three quarters of the way back to point of departure. it said that owing to the time window of the satalite, the object must have been moving at incredible speed to be able to observe the full length of the vapour trail.
A second point of view is, would they have got rid of an asset such as the SR71 without a suitable replacement, as a few years ago when they extended the retirement date due to gulf situation, stating that it was a useful asset due to time required to retask a satalite, when the SR71 could be airborne and on it's way in a fraction of the time.