Detailed Instructions: 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: 'ESS then contracted with Halliburton subsidiary KBR , which in turn billed the government an unknown amount of money for the same security services , according to the paper .', Argument/Subject 1: 'kbr', Argument/Subject 2: 'halliburton'
A:
be subsidiary of