It is rather astonishing that some authors refer to Article 52 of the UN Charter - dealing with Regional Arrangements - as a “legal basis” for carrying out military action against Syria, without Security Council authorization.
By invoking Article 52, they point out to the Arab League and NATO, as regional organizations. Now it is true that the aforementioned Article acknowledges the right to establish regional organizations or agencies, as well as their role in the maintenance of international peace and security, which includes taking “appropriate action” to this effect.
However, those authors seem to read or interpret Article 52 as a “green light” or as a plain authorization for regional organizations - like NATO - to act, even militarily, to maintain international peace and security. I wish that those who invoke Article 52 would care to read the Article that follows.
Article 53(1) of the Charter clearly and expressly states: “… no enforcement action shall be taken under regional arrangements or by regional agencies without the authorization of the Security Council”. Therefore, any argument based on Article 52 is rejected outright.
Furthermore, other authors argue that the right to self-defence, whether individual or collective - affirmed by Article 51 of the Charter - may serve as a “justification”. This is a ridiculous argument. Syria hasn’t used any illegal force against any State. Therefore, this argument is absolutely baseless and rejected.
In conclusion, any military action taken against Syria without Security Council authorization would be in flagrant violation of international law, namely Article 2(4) of the Charter of the United Nations, which prohibits the threat to use or the use of armed force in international relations - except in self-defence, or when the Security Council authorizes measures under Chapter VII of the Charter.