Started in 2011, conflict in Syria is one of the controversial and complicated conflicts that has ever happened so far. It has been put forward by the United States and its allies alleging that the Government of Syria has used chemical weapons against its own people; however, these allegations have never been verified by an authentic entity such as the United Nations or Organization for the Prohibition of Chemical Weapons (OPCW). Despite the situation in Syria regarding the chemical attacks, invading Syria by the US-led coalition is questionable from the perspective of international law and even the national law of the United States.
Before Trump, it was Barack Obama who threatened the government of Syria to perform a military attack because of the alleged Syrian chemical attacks on its people and the violation of human rights and international humanitarian law in Syria; however, there are two main challenges before the United States’ President in attacking Syria, one of which is the “Constitution of the United States”, and the other is “principles and rules of international law”.
1. United States’ Constitution
Although the President of the United States is the “Commander in Chief of the Army and Navy of the United States” (Article 2 – Section 2(1)), the advanced permission of the Congress is necessary to declare a war (Article 1 – Section 8(11)). The permission of the Congress, however, might be eluded when the United States is “actually invaded, or in such imminent Danger as will not admit of delay” (Article 1 – Section 10(3)).
Therefore, according to the United States’ Constitution, Donald Trump as the President of the United States and the Commander in Chief of the Army and Navy can perform a military attack against Syria only on two bases: either obtain the permission of the Congress or act against an imminent attack against the United States.
Self-defense is recognized in both article 51 of the Charter of the United Nations ("an armed attack occurs against a Member of the United Nations; shall be immediately reported to the Security Council; shall not in any way affect the authority and responsibility of the Security Council under the present Charter") and in customary international law reaffirmed by ICJ judgement in Case Concerning Military and Paramilitary Activities in and Against Nicaragua – 1984 (necessary and proportionate).
Obviously, since the United States has not been invaded by Syria, President Trump cannot resort to self-defense principle as the justification for his decision. Granting permission from the US Congress to the Trump administration is the only way President Trump can commence an attack against Syria in compliance with US legal system.
2. Principles and Rules of International Law
According to article 2(4) of the Charter of the United Nations, all Member States of the United Nations are prohibited from “[…] the threat or use of force against the territorial integrity or political independence of any state […]”, even though, there are two exceptions in the Charter to this general principle. Firstly, article 51 of the Charter of the United Nations recognizes the inherent right of individual or collective self-defense when an armed attack occurs. Secondly, the authorized military actions or related decisions taken by the UN Security Council under the Chapter VII (article 42) of the Charter of the UN. It is worth mentioning that the UNSC decisions “shall be made by an affirmative vote of nine members including the concurring votes of the permanent members (article 27(3))”.
If President Trump intents on attacking Syria, he should obtain the permission of the UNSC first, otherwise, any attack against Syria would be illegal within the framework of articles of the United Nations. Even if the United States decides to render a military action on the basis of Responsibility to Protect (R2P), it should also be exercised after the UNSC’s permission.
Above all, according to the article 2 of 2001 “draft articles on responsibility of States for internationally wrongful acts”, an internationally wrongful occurs when it “is attributable to the State under international law” and “constitutes a breach of an international obligation of the State”. In this case and under international law it is crucial that chemical attacks should be attributable to the Government of Syria which has not yet been realized.
Conflict in Syria with three main parties including the Islamic State of Iraq and the Levant (ISIS), Syrian opposition and allies, and the Government of Syria and its allies is a special case from the perspective of international law. Every group in this conflict tries to justify their actions under international norms and questions other parties. Despite the legality or illegality of the activities of the abovementioned groups, using chemical weapons is an act of war crime and violation of international humanitarian law and there is no justification for it.
In conclusion, the following conditions should be observed by the United States relatively in the event they have the decision on attacking Syria:
1. Preceding to any attack against Syria, it should be proved that the chemical attacks were rendered by the government of Syria and those attacks are attributable to that government.
2. Since the US is not invaded, the permission of the US Congress should be obtained by the Trump administration;
3. The permission of the UNSC under chapter VII of the UN Charter is necessary. Otherwise, any attack against Syria would be regarded as a violation of the provisions of the UN Charter.