An intelligence operation has different requirements. While those listed applications might hide the contents of the messages, you can still see that messages w

An intelligence operation has different requirements. While those listed applications might hide the contents of the messages, you can still see that messages were sent/received, and that might be enough to warrant you for summary execution in China. During WW2/WW1 the British knew when air raids were coming from Germany by recognizing radio traffic patterns, and activity. The radio traffic was encrypted, and they could not understand whatever was sent, but the traffic itself created patterns that alerted them.