Again, this doesn't stand up to scrutiny. To pick up radar transmissions reflected off the moon, the moon has to be in line of sight for both the emitter and de

Again, this doesn't stand up to scrutiny. To pick up radar transmissions reflected off the moon, the moon has to be in line of sight for both the emitter and detector. Puerto Rico is just about the worst positioned place in the US for something to have the moon in line of sight at the same time as the soviet union, and the particular design of Arecibo further limits the angles it can be directed at, so it can't even look towards the horizon where it might conceivably stand a chance. It's fine for a telescope as the rotation of the Earth allows it to look at different parts of the sky at different times, but there's a reason no radio receivers for terrestrial communication are built that way. Further, Arecibo works at frequencies of 10-40 MHz, substantially lower than even the lowest frequency radars. With secondary reflections you might be able to detect that a radar pulse had been detected, but determining where it came from or even what emitted it would be extremely challenging. I suppose perhaps Cuba could have been spied upon with it, but again it's just the worst design for the application.