Microsoft says it is suing Samsung for calling a halt to the royalties it was paying Microsoft for patents behind the Android operating system.
The two companies came to a deal in September 2011 to cross-license each other's patent portfolios. Samsung wound up paying Microsoft royalties on a series of patents.
Analyst Rick Sherlund of Nomura Securities has estimated royalties on its Android patents bring Microsoft nearly $2 billion a year.
In a blog post Friday, Microsoft Corp.'s deputy general counsel said Samsung stopped paying royalties late last year after Microsoft announced in September it was acquiring Nokia's devices business, saying that Samsung Electronics Co. Ltd. "began using the acquisition as an excuse to breach its contract."
A Samsung spokesperson could not immediately be reached for comment.