Military engineering is loosely defined as the art and practice of designing and building military works and maintaining lines of military transport and communications. Military engineers are also responsible for logistics behind military tactics. Modern military engineering requires more than civil engineering techniques. In the 21st Century, military engineering also includes other engineering disciplines such as mechanical and electrical engineering techniques. Military engineering is an important academic subject taught in military academies or schools of military engineering. The construction and demolition tasks related to military engineering are usually performed by military engineers including soldiers trained as sappers or pioneers. In modern armies, soldiers trained to perform such tasks while well forward in battle and under fire are often called combat engineers.