Originally posted by sammi jo
*The few major roads between the two nations would have been closely and continuously monitored in the US by spy satellite for suspicious activity, such as truck movements, materials being buried etc. The technology in space is of such high resolution that small text can be deciphered.
Not trying to go too far off topic, but that is a common misconception.
From the Federation of American Scientists(fas.org):
"Imagery intelligence satellites use film and electronic cameras, or radars, to produce high resolution images of objects on the ground at ranges of up to one thousand kilometers. Orbiting at altitudes several hundred kilometers, such satellites can readily identify and distinguish differing types of vehicles and equipment with resolutions better than 10 centimeters. Resolutions of several meters are useful in locating vehicles and characterizing installations, while resolutions on the order of ten meters have some applications for locating facilities, such as airfields and ports.
10cm is good resolution, but not quite enough to read text, and there are only 3 of the modern satellites in orbit at one time that are capable of it.
"Three of the older KH-11s are currently in orbit, as well as three of the more capable Advanced Keyholes, which fly in orbits nearly twice as high as their predecessors."
And during Iraq's invasion of Kuwait(when every asset available was focused on Iraq): "These systems were not infallible, since the US lost track of four Iraqi divisions for a 24 hour period on August 7-8."
During the Cold War, it was quite common for the USSR to time troop/ship movements to times when we had no satellite coverage.
*The movement of high level radiological material is extremely tough to conceal without specialized shielding.
I have hands on experience with industrial radiographic sources, it's not that difficult to shield a radiation source. A couple inches of lead or steel would be more than enough to drop readings down below background. And 'inert', ie, not involved in a chain reaction, uranium actually does not emit much radiation compare to other sources(cobalt, irridium, strontium).