(S (S (BASENP (DT The) (NN airport)) (VP (VBZ serves) (PP (IN as) (NP (NP (BASENP (NNP NATO) (POS 's)) (BASENP (NN operating) (NN base))) (PP (IN for) (BASENP (JJ southern) (NNP Afghanistan))))))) (PERIOD .))