When we want to make something go across nation's border behind police, what would you do?
The answer is that what crosses border must be enough small not to be detected by police.
I've heard that a man who tried to exile to United States from Cuba navigated a small airplane without using rader. As a result, it was not detected by police.
The aircraft was too small to detect in ocean which divides US and Cuba.
On the other hand, it will be impossible to navigate aircraft from Shenzhen to Hong Kong without detection by police. But, drone will be so small that it was not detected by police for a long time.
But, if you repeat it, the possibility to be noticed by police must be increased.
