". . .can anyone explain (I can't understand it) why the Soviets, with 5 million men under arms, tried to pacify Afghanistan with less than 130,000 men?!"
Because that is all they had available for that kind of adventure.
About half their 5 million men did not really have first-line weapons, or logistics available to support them in the field. Much of the Soviet army was used to gather crops during peacetime.
Of the half that was left, about a million were needed to keep an eye on the Chinese, maybe 750,000 to keep Eastern Europe as "allies" (can you say occupation troops?) and maybe half a million to keep the restive people in the Soviet Union under control. That left about 250,000 for active deployment in foreign adventures. They committed about half of that to Afghanistan (and maybe another tenth as advisors, world-wide).
"Of the half that was left, about a million were needed to keep an eye on the Chinese, maybe 750,000 to keep Eastern Europe as "allies" (can you say occupation troops?) and maybe half a million to keep the restive people in the Soviet Union under control. That left about 250,000 for active deployment in foreign adventures. They committed about half of that to Afghanistan (and maybe another tenth as advisors, world-wide)."
If that is true (and I grant you 500,000 MVD and/or uniformed KGB were used for "internal security") then why did a US Army Captain (field artillery) tell me in Dec. 1978 that if the balloon went up that we'd lose half our people in Europe and Ivan would reach the Ruhr no problem. Pretty hard to do that with a couple-hundred-thousand guys who can't suppress a bunch of goat-humping bandits.