3-67. An additional consideration is interoperability of forces. Interoperability is often measured by the ability of multinational formations to execute secure communications, process digital fire missions, and share a common operational picture. Army forces train with unified action partners to ensure interoperability. Working with unified action partners is critical to the Army’s ability to build credible deterrence in any theater. Planners must consider procedural systems that facilitate interoperability when technical capabilities are not compatible.