They don't need to hide anything. This type of activity is playing off of the success of the North Koreans and Russians in neutralizing US power in the face of a completely inept and corrupt government.

The audience is other Asian and African states. The message is "we can act with impunity". The US will probably do some tit-for-tat exchange, but the US scope to do anything is limited due to the potential for impact on US businesses.