Resolution 2249 conspicuously avoided authorizing any military action under Article 51 of the Charter (or any other part of Chapter VII) but spelled out the body of international law "particularly the Charter" that must be observed.
Article 2(7) says
Enforcement measures under Chapter VII are not authorized by 2249. But it calls for "all necessary means" to "eradicate" the safe haven for terrorists in Iraq and Syria.
This is a resolution of weasel words. It calls on members to eradicate terrorists without, once again, giving a clear statement of what terrorism is, except that "terrorists" are people who are then placed on the "1267 committee" terrorism list, an opaque process. So we have circular arguments about who the terrorists are, and contradictory instructions and permissions to member nations who have the capacity to do the unspecified eradication. "All necessary means" presumably does not include nuclear weapons.
A plain reading of the UN Charter seems to make clear that participation in civil wars is forbidden. Whatever is going on in Syria and Iraq is civil war. If the UN Security Council wants something enforced, it should say so and give authorization for military action. Otherwise, shut up.
In our time, political speech and writing are largely the defense of the indefensible. Things like the continuance of British rule in India, the Russian purges and deportations, the dropping of the atom bombs on Japan, can indeed be defended, but only by arguments which are too brutal for most people to face, and which do not square with the professed aims of political parties. Thus political language has to consist largely of euphemism, question-begging and sheer cloudy vagueness. Defenseless villages are bombarded from the air, the inhabitants driven out into the countryside, the cattle machine-gunned, the huts set on fire with incendiary bullets: this is called PACIFICATION. Millions of peasants are robbed of their farms and sent trudging along the roads with no more than they can carry: this is called TRANSFER OF POPULATION or RECTIFICATION OF FRONTIERS. People are imprisoned for years without trial, or shot in the back of the neck or sent to die of scurvy in Arctic lumber camps: this is called ELIMINATION OF UNRELIABLE ELEMENTS. Such phraseology is needed if one wants to name things without calling up mental pictures of them.
Orwell, Politics and the English Language