Drones give nations impunity to overfly other nations air space.
Surprisingly, many states have been overflying their neighbour’s territory with some level of impunity. Israel has overflown Lebanon, and left its drone there for many hours, before departing. Hizbollah has flown drones many times over northern Israel, to the embarrassment of the Israeli military. In 2006 the Israelis shot down at least two Hezbollah drones.
Georgia has overflown South Ossetia, which it claims, but which is controlled by Russia. Here is a video of a Russian MIG shooting down a Georgian UAV, apparently over South Ossetia in 2008.
The US regularly overflies Pakistan with drones, and indeed launches deadly attacks from them. At least two US drones have been shot down recently over North Waziristan.
In 2009 the US shot down its own out of control Predator drone before it entered Tajikistan.
Iran has overflown Iraq, and had at least one drone shot down by US forces. US forces claimed the trespass was intentional, Iranian and Iraqi officials claimed it was an accident.
Why are there so many violations of airspace, using drones? Are they more likely to be used than manned aircraft? Clearly many drones are surrepticious, difficult to detect, and difficult to shoot down because of their size, especially without collateral damage on the ground. Because most drones are clearly for surveillance, the country sending the drone may feel they can get away with incursions even if detected, because they are a ‘minor’ threat.