Article 51

The Iraqi air strikes in Syria on Friday have inevitably brought up the question of their legality.  The highly probable answer is that the air strikes were legal under international law.
If the air strikes were carried out with the prior permission of the Syrian government, then the question of their legality does not exist: the Iraqi air strikes would be legal, just as Russian air strikes which happen in Syria are.

Violation of the UN Charter and the Nuremberg Principles
In recent years, participation in NATO has made European countries accomplices in US efforts to achieve global hegemony by means of military force, in violation of international law, and especially in violation of the UN Charter, the Nuremberg Principles.