The legal obligations of a State participating in combined operations do not change when its armed forces are operating in a multinational force under the command or control of a military commander of a different nationality.
- The obligations of any State under international law are based on customary law and on any treaties to which it is a Contracting Party. These obligations do not change when the State participates in a combined operation with States that have different obligations. This is the case even when the commanding officer of the combined operation comes from a State that has different treaty obligations.
- The problem transcends the issue of different treaty obligations undertaken by partners in a combined operation (see Commentary on Rule 161). It is a common phenomenon for States which are Contracting Parties to the same treaty to interpret certain clauses of that treaty in a different way, just as States often differ in their interpretation of customary international law. This would be an issue of legal interoperability (see Rule 164). A good example of the latter phenomenon involves the divergent approaches to the application of the principles pertaining to military objectives (see Section E, especially paragraph 2 of the Commentary on Rule 24). Specifically, two or more partners to a combined operation may have different interpretations of the law of international armed conflict as regards targeting in a manner affecting their respective assessment of the legality of a particular bombing mission. The result may be that one partner in the combined operation may be willing to undertake the mission, whereas another may not. The question that arises is whether the latter State may nevertheless provide the former with escort fighter aircraft, while the bombing itself is conducted by a bomber of the former State.
- One way of resolving such issues is by using common Rules of Engagement as a tool. A State may agree to Rules of Engagement that are more restrictive than its obligations under the law of international armed conflict (as it interprets it), in order to be in harmony with the conduct of partners in the combined operation or for other reasons.
- Another way is to permit partners in the combined operation to insert “caveats” if they find common Rules of Engagement to be too “robust”. This is done before an operation commences or when the common Rules of Engagement of an ongoing combined operation are to be reconsidered. Such caveats may be based on legal, as well as political or other reasons. A partner in the combined operation may find it necessary to put certain restrictions on the operations of its troops, in order to maintain sufficient domestic political support for its participation in the combined operation. Caveats may also be based on reasons that have a technical basis, such as when one partner in the combined operation has less accurate weaponry at its disposal than other partners in the combined operation, and therefore finds it necessary to apply stricter Rules of Engagement for its forces in order to keep the risk of collateral damage at a sufficiently low level.
- Such caveats will give other partners in the combined operation advance notice of a partner’s inability or unwillingness to undertake certain tasks, thus enabling the force commander of the combined operation to adapt plans accordingly. This is typically done by applying a “troops to task” solution, which means that particular tasks are assigned to troops that are not barred from executing them by caveats. In combined operations with many partners and a substantial number of caveats, the commander may use a matrix that shows which troops can be assigned which tasks.
- For reasons of operational efficiency, and in order to keep planning simple and reduce the potential for misunderstandings, force commanders would prefer to have the least possible number of caveats to the common Rules of Engagements from the partners in the combined operation. However, the legal and political constraints may be such that this becomes unavoidable.
- It is up to the partners in a combined operation to decide how to organize the decision-making process. One solution may be to have a collective body, typically with representatives from all partners in the combined operation, undertaking analyses of proportionality and other requirements of the law of international armed conflict and deciding on targeting issues. When such a collective procedure is adopted, each partner to the combined operation may have the power to impose a veto barring any particular attack. The imposition of veto is called “red card” procedure. If a partner in the combined operation “shows the red card” with regard to a particular attack that is being planned, the attack will have to be cancelled.
- Another way to organize the decision-making process may be to vest the authority to make targeting decisions not with the operational commander alone, but allowing partners in the combined operation the use of a “red card” to preclude assignment of particular missions to their respective forces, in accordance with their caveats (see paragraphs 4 − 6 of the Commentary on this Rule) or for other reasons. Under this arrangement, the operational commander may still be able to carry out his plan, but only if he has at his disposal forces that are able and willing to execute it.
Categories: Section W: Combined Operations