In recent years the dilemmas posed by NATO's heavy reliance on nuclear weapons for deterrence and defense in Europe have created significant strains within the NATO Alliance between the United States and Western Europe and between NATO and the Warsaw Pact. These dilemmas include the political liabilities for Western Europe of dependence upon an American decision to use or not to use nuclear weapons in a conflict, security liabilities resulting from the declining credibility of NATO's deterrent and from high risks of escalation to the nuclear level in crisis situations, and liabilities resulting from the undermining of East-West detente and the reappearance of tensions and arms races in Europe.