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).
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).