TOI reported:
Police sappers were called to the Israel-Gaza border area on Saturday after a balloon suspected of carrying an explosive device landed in Israeli territory.Assuming 12-inch diameter latex balloons, it would take 29 of them to handle a payload of a pound.
Hebrew media reported that the balloon was carrying a warhead from an anti-tank missile.
If Gaza terrorists wanted to send a 5 kg explosive - about the size of the explosives used by suicide bombers - they could do it with 315 balloons.
But it would be easier to obtain a much larger balloon.
A balloon 6 feet in diameter is less that $30 online and it can lift 7 lbs. An 8 foot balloon is less than $80 and can carry 17 lbs.
These would require a lot of helium (or propane, which is probably easier available in Gaza but have only half the lift.) But there seems to be enough helium in Gaza already.
This is not a trivial issue.