IIRC, the conclusion at the time was that that particular image was taken by an NRO KH-11 satellite - roughly equivalent to a Hubble Space Telescope pointed at earth and definitely not SAR.
Supposedly this was taken by a KH-11 Block 4 (USA-224) which means this is cutting edge as of 2005. We're currently on Block 5 as of 2018.
The biggest secrets within US Reconnaissance Satellites isn't really optical clarity anymore, it is their capabilities in other spectrums (and have supported at least infrared for 30+ years, but with signals intelligence well beyond that since).
More like standard optical image(the resolution and details are amazing, if it's a satellite, which is doubtful given the angle).