America is under attack.
( America ( ( is ( under attack ) ) . ) )
(ROOT (S (NP (NNP America)) (VP (VBZ is) (PP (IN under) (NP (NN attack)))) (. .)))
Someone or something is attacking America.
( ( ( Someone or ) something ) ( ( is ( attacking America ) ) . ) )
(ROOT (S (NP (NN Someone) (CC or) (NN something)) (VP (VBZ is) (VP (VBG attacking) (NP (NNP America)))) (. .)))