With the recent downing of a US drone by Iran, the most pertinent question at this point is: “Where was the drone when it was shot down?” With accurate coordinates, we can easily verify whether it had strayed into Iranian-controlled, national airspace, or if it remained beyond in international airspace.

However, accurate coordinates are more difficult to come by when dealing with 3-dimensional space, and both the Government of Iran and the Government of the US have supplied a different set of coordinates as to the location of the drone before it was shot down. Rather than getting lost in the weeds over where the event took place, in this post we want to briefly discuss the customary international laws defining sovereignty limits on the earth’s surface and above it, namely UNCLOS-III, and the zones of jurisdiction it defines.

National v. International Airspace

Simply put, airspace is divided into two categories, “national” and “international.” These classifications are based on whether the surface of the earth directly below is part of the sovereign territory of a recognized independent state, or not:

National airspace corresponds with that out to the edge of the territorial sea of a state, including archipelagic waters, internal waters, and the land itself. Under the Law of the Sea, a coastal state can claim up to a 12 nautical mile territorial sea from its baselines (either the low tide coast or simplified, straight-line segments declared as “straight” or “archipelagic” baselines). Out to the edge of the territorial sea, a state has “full” sovereignty and jurisdiction equivalent to that on its land. For an unrelated, interesting exercise I did on territorial sea limits, check out this post.

International airspace is that beyond the territorial sea, corresponding to a state’s contiguous zone, exclusive economic zone, and outward into the high seas. The contiguous zone is the maritime space between 12 and 24 nautical miles from a state’s baselines, where they can exercise some authority relating to wrongful activity committed within their territorial sea. The exclusive economic zone (EEZ) is the space between 12 and 200 nautical miles from the baselines, where a state has some extended sovereignty for economic purposes (fishing, oil exploration, etc). The high seas are areas beyond the 200 nautical mile EEZ.

Where was the Drone?

A coordinate about 4 nautical miles inside the Iranian territorial sea limit was supplied by Iranian officials, while the United States submits an entirely different location, closer to the center of the Strait of Hormuz and beyond any state’s territorial waters. Without clarity on the true coordinate and the path of the drone it is difficult to draw any clear conclusions, but the drone was either within Iran’s national airspace as they claim, or not.

In any case, if either of the locations supplied are even remotely accurate, the drone would’ve been downed in either the Iranian territorial sea or EEZ, or in the EEZ of Oman (in this vicinity it also would’ve been in the contiguous zone of either state as well, however this is likely irrelevant). As discussed above, none of these are classified as international waters, but the airspace over the EEZ would be considered international airspace.

Bonus: Attempts to Verify the Location

With the right satellite image captured at the right time, it would be possible to gather some evidence to independently verify the location this incident took place. As civilians, we don’t have ready access to high resolution, “on-demand” satellite imagery, however we often look to open satellite data sources such as the European Space Agency’s Sentinel or Landsat to derive data or make temporal observations.

Reports indicate that the drone was downed June 19^th at 23:35 UTC. A search of Sentinel imagery shows a capture available in the vicinity on the 20^th at 06:52:28 UTC. Unfortunately for us, though, the image does not quite extend to our area of interest.

If we could find an image in close proximity to the alleged time of the incident, we might look for increased maritime activity in a particular location or a debris field from the downed drone. However Sentinel imagery captured June 23^rd shows no signs of either. It is also likely commercial satellites would have captured something, so we might keep our eyes out for imagery from this time period as it becomes available. In the meantime, though, we’ll just keep following the developing story surrounding this incident.