barbed-wire fences. The upgrade programme continued well into the 1980s. The new system immediately reduced the number of successful escapes from around 1,000 people a year in the mid-1960s to only about 120 per year a decade later. The introduction of West German Chancellor Willy Brandt's Ostpolitik ("Eastern Policy") at the end of the 1960s reduced tensions between the two German states. It led to a series of treaties and agreements in the early 1970s, most significantly a treaty in which East and West Germany recognised each other's sovereignty and supported each other's applications for UN membership, although neither state changed its view on the citizenship issue. Reunification remained a theoretical objective for West Germany, but in practice that objective was put aside by the West and abandoned entirely by the East. New crossing points were established and East German crossing regulations were slightly relaxed, although the fortifications were as rigorously maintained as ever. In 1988, the GDR leadership considered proposals to replace the expensive and intrusive fortifications with a high-technology system codenamed Grenze 2000. Drawing on technology used by the Red Army during the Soviet–Afghan War, it would have replaced the fences with sensors and detectors. However, the plan was never implemented. Economic and social impact The closure of the border had a substantial economic and social impact on both countries. Cross-border transport links were largely severed; 10 main railway lines, 24 secondary lines, 23 autobahns or national roads, 140 regional roads and thousands of smaller roads, paths and waterways were blocked or otherwise interrupted. The tightest level of closure came in 1966, by which time only six railway lines, three autobahns, one regional road and two waterways were left open. When relations between the two states eased in the 1970s, the GDR agreed to open more crossing points in exchange for economic assistance. Telephone and mail communications operated throughout the Cold War, although packages and letters were routinely opened and telephone calls were monitored by the East German secret police. The economic impact of the border was harsh. Many towns and villages were severed from their markets and economic hinterlands, which caused areas close to the border to go into an economic and demographic decline. The two German states responded to the problem in different ways. West Germany gave substantial subsidies to communities under the "Aid to border regions" programme, an initiative begun in 1971 to save them