In 1942 another threat emerged when the United States Army Air Force (USAAF) began bombing raids against targets in Belgium and France. The first operation was carried out on 29 June 1942. On 27 January 1943 it extended the American area of operations into Germany for the first time. In 1942 the USAAF flew 1,394 bomber and 1,081 fighter sorties over Western Europe. Sperrle's fighter pilots carried the burden of the defence in 1942. Later that year, JG 1 was assigned to "Luftwaffenbefehlshaber Mitte", later known as "Luftflotte Reich" (Air Fleet Reich) but saw little action since USAAF rarely crossed into the Netherlands. Thereafter, the air war only escalated. Sperrle resisted attempts by "Luftwaffenbefehlshaber Mitte" to gain control of anti-aircraft forces or to allow the physical degradation of his air fleet, and the offensive mindedness of the OKL favoured front-line units. Eventually, "Luftflotte" 3 lost "Luftgau" VII, XII and XIII's anti-aircraft units.