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The developments during World War II continued for a short time into the post-war period as well. In particular the U.S. Army set up a huge air defence network around its larger cities based on radar-guided 90 mm and 120 mm guns. US efforts continued into the 1950s with the 75 mm Skysweeper system, an almost fully automated system including the radar, computers, power, and auto-loading gun on a single powered platform. The Skysweeper replaced all smaller guns then in use in the Army, notably the 40 mm Bofors. In Europe NATO's Allied Command Europe developed an integrated air defence system, NATO Air Defence Ground Environment (NADGE), that later became the NATO Integrated Air Defence System.

Which military set up a large air defence network surrounding its larger cities?
the U.S. Army