1 Constituting infringement

First of all, trademarks are territorial. Company B is the right holder of the "m" trademark in the United States, and its scope of rights is limited to the United States. Secondly, Company D is the right holder of the “m” trademark in China. Company c's sales of goods with this trademark violated Article 52 of the Trademark Law and constituted infringement.

2

The best thing you can do now is to quickly communicate with Company B about this incident and negotiate a solution.