Review on legitimacy of Iran's military presence in Syria based on Int. Law

Assisting Syrian government by the means of counselling in the battle against opposed militia and extremist groups, Iranian government has played some acts in Syrian civil war; particularly in the case of ISIS which is considered as a major threat to the international security as well as Iran’s security. Iran had even launched missile to ISIS positions in Syria; of course, in a specific situation. This article is to investigate whether these interventions are legitimate.
Considering the “prohibition of use of force by states”, Iran’s interventions in Syria can be considered in full accordance with international law on the basis of two factors. First is based on the official invitation of the Syrian legitimate government. As Assad’s government is the legitimate government of Syria, it has the right to invite a foreign country as an ally so as to preserve and defend its legal position. Second on the fact that collective and individual defense against non-state actors is legitimate. Considering the inability of Syrian government in preventing extremist’s actions, namely ISIS, against the security of other states, and also considering the necessity of appropriate military operation performed by Iran, the latter factor would be justified.