How, pray tell, do we see through clouds, except with radar...
Synthetic Aperture Radar (SAR) - like you mentioned
Shortwave Infrared (SWIR) - Can get just about as good resolution as optical
Confocal Diffuse Tomography - The newest, though I'd argue it's been a military technology for at least 20 years. (And that's an educated guess not from personal knowledge) And with the advent of AI, processing the data from this technique can be done in real time.
SAR is good, also the usual beam-directed radar. SWIR will be blocked by clouds (water absorption spectrum). Current laser weapons operate near 1 micron, and we never considered them anything other than clear-weather weapons. SWIR is also blocked by smoke. As for confocal diffuse tomography, it may work in the laboratory, but a battlefield is not forgiving. What would be the basis for thinking it has been "a military technology for at least 20 years"?
SAR is good, also the usual beam-directed radar. SWIR will be blocked by clouds (water absorption spectrum). Current laser weapons operate near 1 micron, and we never considered them anything other than clear-weather weapons. SWIR is also blocked by smoke. As for confocal diffuse tomography, it may work in the laboratory, but a battlefield is not forgiving. What would be the basis for thinking it has been "a military technology for at least 20 years"?