Facebook hit back at Yahoo today with a counter-lawsuit, which claims the crumbling Internet giant infringed on a variety of its software patents, reports AllThingsD. The move comes just weeks after Yahoo filed its initial lawsuit against the social network, alleging its own cacophony of infringements.

“From the outset, we said we would defend ourselves vigorously against Yahoo’s lawsuit, and today we filed our answer as well as counter-claims against Yahoo for infringing ten of Facebook’s patents,” said Ted Ullyot, general counsel of Facebook. “While we are asserting patent claims of our own, we do so in response to Yahoo’s short-sighted decision to attack one of its partners and prioritize litigation over innovation.”

The ten patents Facebook claims Yahoo infringed upon cover a wide range of Web technologies, including link-sharing techniques, tagging, photo-sharing, and online advertising, among others. To see a detailed list of the patents in question, click here.

Yahoo immediately responded to Facebook’s counter-suit, which many knew was in the pipeline.

“We have only just received Facebook’s answer and counterclaims, but on their face we believe they are without merit and nothing more than a cynical attempt to distract from the weakness of its defense,” wrote Yahoo. “As we have made clear from the outset, the unauthorized use of our patented technology is unacceptable and must be resolved appropriately. Other leading companies license these technologies, and Facebook must do the same or change the way it operates. We have proposed that Facebook join us in discussions to resolve the matter, but our overtures have been rejected. As a result, we are prepared to continue to seek redress through the courts.”

Many see Yahoo’s decision to go up against Facebook as the last battle cry of a dying empire. The company will reportedly announce a massive round of layoffs on Wednesday, Yahoo’s staff currently includes about 14,000 employees. Reports suggest the layoffs could see thousands of Yahoo workers lose their jobs — a clear sign of just how badly the company is struggling to stay afloat.

Facebook, on the other hand, is about to go public, and has been valued at somewhere around $100 billion. In other words, it’s clear that these two companies are currently moving in opposite directions, overall, even if they’ve currently stalled one another while passing each other by.

Read Facebook’s lawsuit filing below:

Facebook v. Yahoo