From Your link to the March "Al-Battar Magazine"
"THE “DEAD BOX”
[Summary]
It is a place where materials of any nature can be left at (intelligence reports, weapons, equipment, and so on) for another individual to pick up without a direct contact between the two parties. The Box should match the cover or the disguise –meaning the appropriate security measures – taken by both the loading and unloading entities. It should allow frequent visits of both parties without raising any suspicion. It must be easily identifiable, quickly accessible, well protected from the elements, difficult to monitor by the enemy. It must be located in public places visited by a lot of people such as parks, museums, mosques, restaurants, hospitals and restrooms."
Make one wonder if all the suit cases and boxs being found could have been placed there for such future purposes.