In 2011, Huawei and Samsung began negotiating cross-licenses for their patent portfolios, which includes SEPs.Because both parties are SEP holders, they had mutual obligations to offer each other FRAND licenses. However, they failed to reach an agreement after years of negotiating. Having reached a deadlock, Huawei filed lawsuits against Samsung in the US on 24 May 2016 and China on 25 May 2016. In retaliation, Samsung filed lawsuits against Huawei in the US and China, along with various counterclaims and requests for patent invalidations.As of 13 April 2018, the parties were involved in 42 patent infringement actions in China.