The U.S. Air Force is increasing the number of space-based war games from 2 to 3 in 2019, a move highlighting an emphasis on new space defense tactics in the face of Chinese and Russian satellite warfare developments. Details of the war games are not being released, but the organizing officer has confirmed that they are for the purpose of generating tactics for the protection of U.S. and allied satellites.  

Source: U.S. Air Force to expand Space Flag satellite war game | Aerospace America