Pick the case, Journal Article, or Report that said this: $[$An armed attack$]$ include$[$es$]$ not merely action by regular armed forces across an international border, but also "the sending by or on behalf of a State of armed bands, groups, irregulars or mercenaries, which carry out acts of armed force against another State of such a gravity as to amount to$"($inter alia$)$ an actual armed attack conducted by regular forces.

Eugene V$.$ Rostow, Until What? Enforcement Action or Collective $$elf$-$Defense.

The Chilcot Report

Nicaragua v$.$ US$,1986$

Security Council Resolution $1441$

Security Council Resolution $678$