Combat readiness is a linchpin of Army policy, and military exercises up to divisional level are conducted many times yearly, simulating full-spectrum operations, up to and including full-scale war. Divisional war games are a combined arms, tri-service affair involving the Republic of Singapore Navy and Air Force. Because training space is limited in Singapore—artillery fire would quickly traverse the island—some military exercises are conducted overseas. Reservists periodically train abroad, their units regularly evaluated for combat readiness. The Army also trains bilaterally with some host nations, and military exchanges are frequent. Training is billed as "tough, realistic and safe," with a premium on safety, given the sensitivity of military deaths in a largely conscript army.