rb wrote:

Highly unlikely that it went undetected for 25 mins.
More likely it's Iranian sabre rattling again.

Regardless of the accuracy of this particular account, it is true that
UAVs pose a new problem for navies and armies, especially in the
smaller versions. Defensive systems are generally designed to detect
and destroy much bigger and more obvious targets, and even if they
manage to spot a small UAV, what would be used to shoot it down?

This is the subject of much debate at the moment. Ordinary homing
missiles may not be able to lock-on to a stealthy little UAV (and even
if they could, there's not much logic in using a very expensive missile
to shoot down a very cheap plane). A radar-directed gun system like
Phalanx might also not lock-on to such a target. The best bet at the
moment IMO would be a 35mm gun firing the Oerlikon AHEAD 'shrapnel'
type airburst ammo, using electro-optical guidance.

Tony Williams: Military gun and ammunition
website and discussion
forum