As the lead pilot explained, I reverted to the Russian threat.
( ( As ( ( the ( lead pilot ) ) explained ) ) ( , ( I ( ( reverted ( to ( the ( Russian threat ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN As) (NP (NP (DT the) (JJ lead) (NN pilot)) (VP (VBN explained)))) (, ,) (NP (PRP I)) (VP (VBN reverted) (PP (TO to) (NP (DT the) (JJ Russian) (NN threat)))) (. .)))
The Russian threat was revisited.
( ( The ( Russian threat ) ) ( ( was revisited ) . ) )
(ROOT (S (NP (DT The) (JJ Russian) (NN threat)) (VP (VBD was) (VP (VBN revisited))) (. .)))