Since the end of the Cold War, NATO has experienced the great challenges of the disintegration of the Soviet Union and the end of the Cold War. The Atlantic Alliance, albeit in a stage of crisis due to the US-Europe rift after Trump's election, has been preserved as a legacy of the Cold War, but the Warsaw Pact has not been able to escape dissolution. In Asia, although there is discord around the issue of military bases in Okinawa, the US-Japan alliance is still firmly rooted, while the Sino-Soviet military alliance only survived in name until as early as the mid-1960s. From this point of view, the vitality of alliance diplomacy is different. Similarly, quasi-alliance diplomacy has its own vitality. Some countries have maintained their quasi-alliance for decades like the United States and Saudi Arabia since the 1960s. But other quasi-alliances, such as Syria and the United States during the Gulf War in 1991, were ad hoc. What are the causes for the termination of quasi-alliance? Why would some quasi-alliances survive the tests of a changing environment? What influences could the internal relations of quasi-alliance members have on the longevity of alliance? This chapter analyzes the end of quasi-alliance diplomacy from the international system level, the national level and the unit level.

The System Level

There are a variety of complex factors for the end of quasi-alliance diplomacy. If a state disintegrates, the quasi-alliance will naturally end. No matter how unpredictable the diplomatic acts are, the decisions made by the decision-makers often are the results of changes in the international situation, that is, changes in the international and regional systems will inevitably lead to changes of the national identity, which, in turn, will have an impact on the decision-makers’ judgment of the interests, eventually forcing the decision-makers to reassess the country's diplomatic orientation. When the gap between expectations and reality widens rapidly, it will be irreversible for the end of quasi-alliance.