self-propelled K55 and K9 Thunder howitzers and 680 helicopters and UAVs of numerous types, are assembled to provide additional fire, reconnaissance, and logistics support. South Korea's smaller but more advanced artillery force and wide range of airborne reconnaissance platforms are pivotal in the counter-battery suppression of North Korea's large artillery force, which operates more than 13,000 artillery systems deployed in various state of fortification and mobility. The South Korean Navy has made its first major transformation into a blue-water navy through the formation of the Strategic Mobile Fleet, which includes a battle group of Chungmugong Yi Sun-sin class destroyers, Dokdo class amphibious assault ship, AIP-driven Type 214 submarines, and King Sejong the Great class destroyers, which is equipped with the latest baseline of Aegis fleet-defense system that allows the ships to track and destroy multiple cruise missiles and ballistic missiles simultaneously, forming an integral part of South Korea's indigenous missile defense umbrella against the North Korean military's missile threat. The South Korean Air Force operates 840 aircraft, making it world's ninth largest air force, including several types of advanced fighters like F-15K, heavily modified KF-16C/D, and the indigenous T-50 Golden Eagle, supported by well-maintained fleets of older fighters such as F-4E and KF-5E/F that still effectively serve the air force alongside the more modern aircraft. In an attempt to gain strength in terms of not just numbers but also modernity, the commissioning of four Boeing 737 AEW&C aircraft, under Project Peace Eye for centralized intelligence gathering and analysis on a modern battlefield, will enhance the fighters' and other support aircraft's ability to perform their missions with awareness and precision. In May 2011, Korea Aerospace Industries Ltd., South Korea's largest plane maker, signed a $400 million deal to sell 16 T-50 Golden Eagle trainer jets to Indonesia, making South Korea the first country in East Asia to export supersonic jets. From time to time, South Korea has sent its troops overseas to assist American forces. It has participated in most major conflicts that the United States has been involved in the past 50 years. South Korea dispatched 325,517 troops to fight alongside American, Australian, Filipino, New Zealand and South Vietnamese soldiers in the Vietnam War, with a peak strength of 50,000. In 2004, South Korea sent 3,300 troops of the Zaytun Division to help re-building in northern Iraq, and was the third largest contributor in the coalition forces after only the