Given a sentence and two mentions from the text (arguments), indicate a phrase (a verb or noun phrase) that describes the relationship between the provided arguments.
Q: Sentence: 'Bodman 's letter to Sen. John Warner , R-Va. , chairman of the Senate Armed Services Committee , said his department would " continue to explore ways to accelerate its schedule for this important mission . "', Argument/Subject 1: 'warner', Argument/Subject 2: 'senate arm service committee'
A:
be chairman of