Apple is suing one of its most important suppliers (AAPL, QCOM)

Apple is suing Qualcomm, according to a lawsuit filed in federal court seen by Business Insider. 
Apple buys wireless chips from Qualcomm and also pays it license royalties to use its wireless patents.
Apple is accusing Qualcomm of withholding $1 billion in rebates under a deal they had struck to keep Qualcomm modems in Apple products, including the iPhone and iPad. 
Qualcomm held the rebates after Apple worked with Korean anti-trust regulators looking into Qualcomm's licensi