It all started in February, when the Redmond company decided to sue TomTom for the alleged infringement of eight Microsoft patents.

This week brought the legal answer from the GPS maker: the company accuses Microsoft of infringing four TomTom patents, all of them related to vehicle navigation software. The coutersuit was filed in the US District Court for the Eastern District of Virginia

While TomTom’s repsentatives chose to remain silent for the time being, Microsoft’s Horacio Gutierrez, corporate vice president and deputy general counsel of Intellectual Property and Licensing, came up with the following statement:

"We are reviewing TomTom’s filing, which we have just received. As has been the case for more than a year, we remain committed to a licensing solution, although we will continue to press ahead with the complaints we initiated in the U.S. District Court for the Western District of Washington and the International Trade Commission."