U.S. experts who have looked at his previous creations characterize him as a genius at the miniaturization of bombs.
1947, from miniaturize + -ation. Minification in this sense attested from 1904, on analogy of magnification.
1946, from miniature (adj.) + -ize. Minify in same sense is from 1670s, on analogy of magnify. Related: Miniaturized; miniaturizing.