Drone warfare is a form of warfare using unmanned or autonomous robots. The robots may be remote controlled or have varying levels of autonomy during their mission. Types of robots include unmanned combat aerial vehicles (UCAV) or weaponized commercial unmanned aerial vehicles (UAV), unmanned surface vehicles (USV) or unmanned underwater vehicles (UUV), and unmanned ground vehicles (UGV). The United States, the United Kingdom, Israel, China, South Korea, Iran, Iraq, Italy, France, India, Pakistan, Russia, Turkey, Ukraine, and Poland are known to have manufactured operational UCAVs as of 2019.