Why is the US ramping up production of plutonium ‘pits’ for nuclear weapons?

News Snapshot:

On one side of the US – on New York’s Staten Island – the US army corps of engineers began this month to remove the radioactive remnants of Robert Oppenheimer’s Manhattan Project that produced the atomic bombs that ended the second world war. Meanwhile, 3,000 miles away, at the Los Alamos national laboratory north of Santa Fe in New Mexico, on the same site that developed and assembled the bombs dropped on Hiroshima and Nagasaki, work is being ramped up to produce plutonium “pits” – spherical shells about the size of bowling balls that are a vital component of warheads...