In current military use, combined operations are operations conducted by forces of two or more allied nations acting together for the accomplishment of a common strategy, a strategic and operational and sometimes tactical cooperation. Interaction between units and formations of the land, naval and air forces, or the cooperation between military and civilian authorities in peacekeeping or disaster relief operations is known as joint operations or interoperability capability. Conceptual development Pre-modern history The concept of combined operations evolved largely as a result of expeditionary warfare that can be traced to the Sea Peoples. In its basic form it involved raiding coastal regions by land forces arriving from the naval vessels. The raiding tactics were expanded into more complex operations by Alexander the Great, who used naval vessels for both troop transporting and logistics in his campaigns. The next exponents of combined operations in the ancient world of the Mediterranean Basin were the Carthaginians who introduced two entirely new dimensions to the use of naval forces by staging not only operations that combined naval and land troops, but also eventuated in combining strategic multi-national forces during the land phase of the operation when Hannibal in his most famous achievement at the outbreak of the Second Punic War marched an army that included war elephants, from Iberia over the Pyrenees and the Alps into northern Italy. Following the example of Carthage, the Romans used combined operations extensively to expand their Empire and influence in the Mediterranean and beyond, including the Roman conquest of Britain, which was not only a temporary expeditionary operation but included long term occupation and Roman settlement of the territories. Following the peace agreement between Kush and Rome in 21 BC, the Kushites and Romans performed joint military operations against several adversaries. The next development of combined operations came from environmental pressures in the Scandinavian region during the Middle Ages, and the emergence of the Viking migrations that combined raiding, longer term inland operations, occupation and settlement. These operations were conducted as sea, coastal, and riverine operations, and sometimes were strategic in nature, reaching as far as Constantinople. In Southeast Asia, the development of combined operations proceeded along the same developmental path as in Europe with the raids by the Wokou, or so-called "Japanese pirates". Because the Wokou were weakly resisted by the Ming Dynasty, the raiding eventually developed into fully fledged expeditionary warfare with the Japanese invasions of