Them!

Perhaps no other cold war era sci-fi film is as nonthreatening as Them!  Because of nuclear bomb tests, ants have grown to massive size and threaten to destroy the world, kind of.  Although the characters speak of unimaginable terror and destruction, all the ants do is tear down some wooden walls and hide in a hole for the rest of the movie.  The team of characters, led by a scientist and his scientist daughter, plan to kill all the ants in their nest before they can multiply and spread out, but they fail.  Later, the military is called to Los Angeles as giant ants were spotted going into the sewers.  Eventually the military kills all the ants in the sewer, and then wonder how many others are out in the world as a result of other nuke tests.  This film is closely related to the Japanese Gojira movie.  Nuclear tests have created mutated animals that want to destroy civilization.  The only difference is that in Them! there are a lot of ants.  The effects of radiation from the bombs is more evident as there are many ants irradiated.  In Gojira, there is only one giant monster.  The audience might make the assumption that the lizard that mutated into Gojira was unique enough to begin with, otherwise there would be a lot of Gojiras.  They make up for this by having Gojira completely demolish the city.  The opposite is true in Them.  There are so many ants, but they do so little damage to anything.  This might be interpreted as pointing to the destructive capability of nuclear weapons without explicitly showing their actual destructive power.  Whatever the case, have a large number of ants definitely gives the sense that nuclear weapons are a worldwide problem, and not just a singular, local issue.