 Welcome back. The issue I'm going to address now is very controversial and it relates to the right of states to use force in self-defense and eventually in collective self-defense against terrorist organizations. And before addressing that issue, let me say a few words about terrorism and international law in general. First, and despite many attempts and also many ongoing debates, there is not yet one universally agreed definition of terrorism. And this is because, as the newspapers say, one man's terrorist is another man's freedom fighter. However, there are about 16 international conventions relating to terrorism. Those are sectarial conventions dealing with terrorist attacks against civil aviation, diplomatic agents, maritime navigation, fixed platforms, terrorist bombings, nuclear terrorism, etc. There are also conventions on the suppression of the financing of terrorism. And those universal instruments concluded under the UN auspices are often completed by regional treaties. And those treaties usually contain obligations by which the contracting states must prosecute or extradite alleged offenders and other criminal justice cooperation mechanisms. And the fight against terrorism is indeed first and foremost a law enforcement and criminal justice issue. And further, if a state is attacked by a terrorist group which is present on its own territory, there is no doubt that that state is entitled to take all the police and law enforcement measures needed to protect its citizens and arrest, detain and prosecute the alleged terrorists. Of course, all this must be done in conformity with human rights. But in the course of those law enforcement operations, terrorists might eventually get legally hurt or even killed. The use of police or military force against a terrorist group or organization present on the territory of the state does not need to be justified under the right of self-defense. And as we called earlier, the use of force by a state on its own territory does not come within the purview of the prohibition to use force under article 2 paragraph 4 of the UN Charter. And as we called earlier also, the territorial state may ask help and military assistance from other states and it may invite them to fight the terrorist organization alongside with him. And again, there is no need to refer to collective self-defense for that matter. Consent by the territorial state is, as a matter of principle, a sound and sufficient legal basis. If the intensity of the fighting is such that it reaches the threshold of a non-international armed conflict, the use in bellow applicable to such conflicts might be applicable. But this is an issue of international humanitarian law that I have unfortunately no time to cover. The issue of self-defense within the meaning of article 51 only arises when the terrorist group is not present on the territory of the victim state and that the victim state suffered a terrorist attack which, because of its scale and gravity, can be qualified as an armed attack. Or if the state is suffering from a pattern of several ongoing terrorist attacks, those terrorist attacks accumulate and reach that threshold. And there is no doubt that from a material point of view, attacks by terrorist organizations can reach the gravity threshold of armed attack within the meaning of article 51. It is a very sad fact of life that we have painfully learned at the very beginning of the 21st century as the memory of the attacks of 9-11 immediately comes back in mind. So the issue is not to know if terrorists are capable of carrying out armed attacks. Unfortunately, they are. When an armed attack is of a sufficient gravity and when it is carried out by a terrorist group from abroad, the question is to know whether the victim state may use force in self-defense. The question must be clearly understood and let me explain it. If the attack has been carried out materially by a terrorist group, but if that wrongful act can be legally attributed to a foreign state, then the issue of self-defense against the group will not arise. And the victim state will have the right to use force in self-defense against the state responsible for the attack, even if the attack was materially carried out by the terrorist group. And you may remember what was said during week six when discussing article eight of Arciois. If it is established that a foreign state has instructed a terrorist organization to carry out an attack, the attack will be attributed to that foreign state. And that foreign state will be internationally responsible for the attack. And likewise, if the foreign state has directed the terrorist operation or if it has exercised effective control over the terrorist group in the course of the attack, it will also bear responsibility for it. And in those circumstances, the attack is materially carried out by a terrorist group, but it is legally attributed to a foreign state. It might be very difficult to prove it, but if established, the armed attack by the terrorist group is deemed to be an armed attack by the foreign state. And there is no doubt that the victim state has the right to use force in self-defense against that state because it is responsible for the terrorist armed attack. And likewise, under article 3G of resolution 3314, I quote, the sending by or on behalf of a state of armbands, groups, irregularities of mercenaries which carry out acts of armed force against another state of such gravity as to amount to the acts listed in the resolution. Or its substantial involvement therein is also an act of aggression. Therefore, the foreign state could be responsible for an act of aggression, triggering the right of self-defense, following its own action of sending armed groups that carry out armed attacks, or following its own substantial involvement in such attacks. So there is no legal problem when the foreign state can be held responsible in relation to a terrorist attack under the rules I just recalled. That state can be attacked in self-defense. But the real problem arises when the terrorist group really acts on its own from abroad without any foreign state instructions, directions, control, or substantial involvement. In that situation, and that situation only, that situation only really relates to the issue of self-defense against terrorist groups. And with that in mind, let us see what is the state of current international law in that regard.