155 4. The General Question of State Responsibility for the Delictual Acts of Another 17. On the question whether the United States was responsible for the delictual acts of the contras, the Appeals Chamber considered that Nicaragua was not correct and reviewed the general question of the responsibility of a state for the delictual acts of another. It appears to me, however, that that question does not arise in this case. The question, a distinguishable one, is whether the FRY was using force through the VRS against BH, not whether the FRY was responsible for any breaches of international humanitarian law committed by the VRS. 18. To appreciate the scope of the question actually presented, it is helpful to bear in mind that there is a difference between the mere use of force and any violation of international humanitarian law: it is possible to use force without violating international humanitarian law. Proof of use of force, without more, does not amount to proof of violation of international humanitarian law, although, if unlawful, it could of course give rise to state responsibility. Correspondingly, what needs to be proved in order to establish a violation of international humanitarian law goes beyond what needs to be proved in order to establish a use of force. This is important because, under Article 2, first paragraph, of the Fourth Geneva Convention, all that had to be proved, in this case, was that an "armed conflict" had arisen between BH and the FRY acting through the VRS, not that the FRY committed breaches of international humanitarian law through the VRS. 19. The foregoing may be borne in mind in considering the Court’s holding in Nicaragua that, by arming and training the contras in the circumstances of that case, the United States had used force. The Court did not declare the nature of any underlying theory. I should not be surprised, however, if it applied a test of effective control, but on the flexible basis that control which is effective for one purpose need not be effective for another, and would interpret the decision that way. Thus, in holding that the United States had used force in arming and training the contras, the Court did not rely on specific instructions, something on which it otherwise laid stress where state responsibility was sought to be founded on the delictual acts of another. In this case, the test of effective control, flexibly applied (as I believe the Court intended it to be), shows that the FRY was using force through the VRS against BH, even if such control did not rise to the level required to fix the FRY with state responsibility for any breaches of international humanitarian law committed by the VRS.