As to who mandates, I do not think I can do any better in answering that question succinctly than to quote the Secretary-General of the United Nations who has appealed to the international community to restore the UN Security Council to what he has called its "pre-eminent position as the sole source of legitimacy on the use of force."
The secretary general faces opposition from the international community.
( z1 face :ARG0 ( z2 person :ARG0-of ( z3 have-org-role :ARG2 ( z4 secretary :mod ( z5 general ) ) ) ) :ARG1 ( z6 oppose :ARG0 ( z7 community :mod ( z8 international ) ) ) )