The artist is showing a hand coming from a box labelled Nuclear Bomb with the 2 leaders of America and the Soviet Union try to keep it controlled. This is a metaphor between the arms race between the Soviet Union and how a single mistake between either of them could cost the lives of millions and also could cause a mass extinction event if the nuclear bombs were ever put in the wrong hands.
As I mentioned above, this could cause every country in the world to be on the highest alert and could even cause mass extinction event if one country were to fire at the other country as the other country would send counter nuclear bombs back at their enemy. This is known as M.A.D (Mutually Assured Destruction). A time where the tension was so high is the Cuban Invasion where American troops were going to directly invade Cuba as Cuba was a thorn in America and now started to become a threat as it moved closer to the Soviets who placed nuclear bombs there. This is to level the playing field as the Americans also had nuclear bombs in striking distance of the Soviet Union in Turkey.
Irrigation is the spreading of water over crops for the purpose of farming. The way it's done can vary, but its general use is as described above. Sprinklers and aboveground canals are two examples of it.
