what do we mean." Two poles minus one might give one, three, four, five and even zero poles. Doyle concluded with undefined number of "many" poles. The mathematical breakthrough occurred two years later in the above-mentioned work by Wohlforth: Two states measured up as polar powers in 1990. "One is gone. No new pole has appeared: 2 - 1 = 1. The system is unipolar." The article by Wohlforth, according to Stephen Walt, broke the theoretical path. In the following decade, the IR research tentatively switched to the unipolar or hegemonic stability, which replaced the balance of power as the focus of intense debate among IR scholars. Charles Kupchan, who since 1991 expects an imminent end to the US hegemony, in 2003 agreed that this hegemony causes the present peace and stability. Until the early 2000s, Jack S. Levy and William Thompson adhered to the main Realist paradigm that hegemonic stability is theoretically impossible because other states would counter-balance. By the end of the decade, however, both engaged in search for the causes of the present hegemonic stability. In 2009, the student and follower of Waltz, Christopher Layne, confessed: "As events transpires, however, the fate of earlier hegemons has not befallen the United States." In the 2010s, more IR scholars accepted the hegemonic stability as a theory most fitting the post-Cold War period. Curiously, one of the classics of the HST, Gilpin, denied the existence of the post-Cold-War hegemony and never applied the theory to this period. In 2002, Gilpin referred to some scholars who define the present system as hegemonic. "Less sanguin observers," however, countered that the bipolar system was supplanted by "chaotic, multipolar world of five or more major powers." The proclamation of the "new world order" he attributed to the end of the Gulf War in 1991, though the proclamation is attested from 1990 and the Gulf War had been regarded as the first test to the already existing new world order. Application United States Although the Hegemonic stability theory is attributed to the 1973 work by Kindleberger and the Realist mainstream rejected it for three decades longer, several scholars since World War II had theorized about the US preponderance of power which is identical in its arguments to the hegemonic stability. Similar arguments ping-ponged in the literature about the American foreign policy until the 2017 Peace through strength promised by Donald Trump. Three scholars described how