Although various ideas have been expressed concerning the use of the airspace above a state’s mainland in the period preceding World War I, the view that a state has full sovereignty over its airspace has come to be adopted as common law due to the intensive use of aircraft during this war. Under international law, any breach of this airspace means a breach of a state’s sovereignty over its territory. A state’s airspace consists not only of the airspace over the mainland, but also that above its territorial waters. Territorial waters can extend until 12 nautical miles off the coast. In the past, many planes – military and civilian for that matter -- that entered the airspace of a foreign country without permission were shot down. Many accidental violations of airspace led to deaths of many innocent people. In 1953, Oliver J. Lissitzyn, an authority on international air law, wrote, “In its efforts to control the movements of intruding aircraft the territorial sovereign must not expose the aircraft and its occupants to unnecessary or unreasonably great danger -- unreasonably great, that is, in relation to the reasonably apprehended harmfulness of the intrusion.” According to this view, a state should not attack an intruding aircraft unless it can reasonably justify that it poses a threat to its country.
Flights of international civilian aircraft are regulated by the International Civil Aviation Organization (ICAO), a specialized UN agency. Moreover, states may also sign bilateral agreements for the regulation of these flights. In 1981, the ICAO called on states not to use weapons against intruding aircraft. In 1983, the USSR shot down a South Korean plane carrying 269 passengers, and in 1988 the US downed an Iranian airliner with 290 passengers on board. The United Nations Security Council (UNSC) passed a resolution condemning the downing of the South Korean plane, and in 1984 it was annexed to the Convention on International Civil Aviation, also known as the Chicago Convention, that states are entitled to demand that intruding aircraft should land at a designated airport. The supplementary provisions also included that “signatory” states should refrain from risking the lives and security of the passengers of a civilian plane and from using weapons on civilian aircraft during a flight. A perusal of the wording implies that the ban is not absolute. Therefore, Lissitzyn’s view still holds. So, an intruding aircraft should first be notified of its breach of the airspace and it should be told to leave the airspace or land at a specified airport, whichever is appropriate. Yet, if it does not comply with these instructions or if there are serious indications of its intention to attack, it can be shot down.
The details of the Turkish jet that was downed by Syria were officially announced, and those states that may have information that conflicts with these details are invited to announce it as well. Apparently, the downed jet is not an attack warplane; rather, it was an unarmed F-4 reconnaissance jet. It was flying on a solo mission over the Mediterranean. Syria’s territorial waters in the Mediterranean Sea extend 12 miles off the coast, which is the maximum distance allowed under international law. The jet violated the airspace above Syrian territorial waters only for several seconds, and upon warning from the Turkish flight center, it left Syrian airspace, but it was shot down by the Syrian air defense system in international airspace about 15 minutes after the breach. Syrian authorities did not contact the jet either during the short breach or afterwards. Therefore, Syria cannot possibly perceive an unarmed jet flying alone as a serious threat.
The jet should have been downed
The accidental breach of Syrian airspace by the downed jet during its reconnaissance flight does not entitle Syrian authorities to shoot it down even in Syrian airspace. As explained above, under international law, Syria had to contact the jet to warn it about the breach and tell it to leave the airspace or force it land at a designated airport. Syria will certainly be held responsible for failure to comply with these requirements. Therefore, the Syrian state must pay an apology and compensation to Turkey. For the worst of it, the Turkish jet was shot down in the international airspace. In addition to the Syrian state’s responsibilities under international law, this also means the breach of Turkey’s sovereignty, which has more serious consequences. The right to self-defense, regulated under Article 51 of the United Nations Charter, is one of these consequences. Indeed, shooting down a state’s warplane by violating its sovereignty can be defined as an armed attack under international law. In response, the attacked state is entitled to self-defense. Whether Turkey will resort to this right will depend on Syria’s attitude.
Under international law, states may unilaterally decide on the form of economic, cultural and political relations with other states. States may also freely decide on their military relations with other states that do not involve the use of force. However, the use of military force is allowed only under cases legitimated by international law. Such a use may be legitimized by the UNSC or by self-defense. Even in the case of self-defense, the UNSC must be notified. What we can gather from the foreign minister’s statements is that Turkey will not opt for a military measure, but push the matter at major states and international organizations. Thus, the attack will be discussed in detail at NATO and the UNSC.
The right to self-defense under international law can be used if a state is attacked or if such an attack will inevitably occur. The attack against the Turkish jet in the international airspace may be considered as such an attack. Any armed response to this attack is legitimate if there is no other option and there is no time for negotiation, and it must be proportional. At this point, it is very unlikely for Turkey to resort to the military option. Turkey has sincerely shared the information available to it and called on other states to do the same, and by doing so, it has asserted its confidence in diplomatic means. Turkey has the right to expect the UN and the international community to react harshly to the attack. The way Syria treated the matter by shooting the jet either intentionally or because of lack of coordination among its security forces is considerably important. As a state that is responsible for this act in violation of international law, Syria must exhibit its regret and pay compensation. It must carefully avoid such acts in the future. Given the lesson learned from the 2010 Israeli attack on a Gaza-bound aid flotilla that left nine Turks dead, the use of military force or more serious consequences may arise if such an attack recurs.
* Professor İbrahim Kaya is an expert on international law at Çanakkale University.