In February 1991 , Poland , Hungary , and the Czech Republic and Slovakia ( as Czechoslovakia ) formed the Visegrád Group to push for European integration under the European Union and NATO , as well as to conduct military reforms in line with NATO standards . Internal NATO reaction to these former Warsaw Pact countries was initially negative , but by the 1991 Rome summit in November , members agreed to a series of goals that could lead to accession , such as market and democratic liberalization , and that NATO should be a partner in these efforts . In subsequent years , wider forums for regional cooperation between NATO and its eastern neighbors were set up , including the North Atlantic Cooperation Council ( later the Euro-Atlantic Partnership Council ) and the Partnership for Peace
1991 Rome summit
1991 Rome summit
Enlargement of NATO