Analysis of information sources in references of the Wikipedia article "Skipjack (cipher)" in English language version.
an attack on the full 32-round Skipjack remains elusive until now. [Paper by the same author as the 2002 attack]
However, I have noted that the inconsistency involved may be more apparent than real. Between the statements cited, and the declassification of SKIPJACK, a paper was published by an academic researcher noting that Feistel ciphers of a particular type, specifically those in which the f-function was itself a series of Feistel rounds, could be proven to be immune to differential cryptanalysis.