Although some may consider as a flawed analogy U.S. President Donald Trump's recent decision on the Paris climate accord, it will remind many of the U.S. Senate's decision after World War I about the establishment of the League of Nations. In unstable times of international systems, the behavior of superpowers on the issues pertaining to the international system become very critical for the future of the world order. After World War I, the U.S. decision generated widespread disappointment around the world and played a role in shaping the behavior of other power centers. The shock in the aftermath of this decision also largely determined the behavior of American intellectuals. Thus, Trump's decision to withdraw from the Paris Climate Accord may be an important turning point in the perception of the United States around the world and expectations concerning its leadership in the international system. The decision comes at a period when there are increasing questions about the nature and future of the international system. After the short unipolar moment of 1990s, today many agree that it would be hard to define the system as such. However, this trajectory is not clear, either. Although there are those who argue the emergence of a multipolar world order, there is not any sign among the other poles concerning their readiness to claim the responsibilities of being such centers of gravity at this point. Because of that, some prefer to call it a uni-multipolar world order of which the U.S. still enjoys being the single most important actor. In addition to this ambiguity of the nature of the international system, the U.S. administration so far has not provided a clear idea about its potential role in this ambiguous global order. The words and phrases "leading from behind", "retrenchment" and now "America first" all provide a fuzzy set of conceptualizations so that some may even consider a soft beginning of isolationism in U.S. foreign policy. However, it is not clear how this selective isolationism will work out in such a globalized and interconnected world. The reactions of other international actors following Trump's decision demonstrated further contributed to this ambiguity. In the immediate aftermath of Trump's statement in which he said the U.S. is pulling out from the treaty and will start to renegotiate for a better deal, France, Italy and Germany made a joint statement underlining that the U.S. cannot unilaterally renegotiate the treaty. The U.N. repeated the same position as well. The reactions from these three European countries were particularly significant considering that the leaders of these countries recently met with Trump both at the NATO and G7 summits. Following these summits, German Chancellor Angela Merkel's statements questioning the U.S.'s reliability concerning the security of Europe was particularly significant given it was probably the first such statements after decades and given that the statement came shortly after Trump's debated address at the new NATO headquarters. This time, following the Paris Accord decision and Trump's statements, French President Emmanuel Macron made a televised statement that appeals to the Americans about the climate accord that ended with the slogan: "Make Planet Great Again". These two statements, of course, are important for the future of the trans-Atlantic alliance and partnership. Soon after the reactions of European countries, China made a similar statement about the Paris Climate Accord, indicating that Beijing will continue to recognize its commitment to cutting carbon emissions. The same day, the Chinese media called on the U.S. to rethink its decision while President Xi Jinping's attendance at an event for green sensitivity was shown on Chinese television. Some considered China's position as an attempt by Beijing to fill the leadership role in the international system. The actions of these other major power centers in the system following this decision needs to be followed closely. It will be important to see the positions on environmental politics and if there will be spillover to other issues that could shift the global roles of these powers. If spillover happens, we may see the first steps of a major transformation of global politics. Then the question becomes what the role of the United States in this new global order is or how U.S. interests would overlap with these new rules that other powers are trying to rewrite. More importantly, in addition to the rhetoric, are these other power centers of the international system ready to bear the responsibilities of the emerging world order? Of course, the position of other countries, including Russia, will also play an important role at this critical time. The decision also raised mixed reactions in the U.S. While some consider this decision as one of the most consequential mistakes in U.S. foreign policy and describe it as a U.S. resignation from the leadership of the free world, others emphasized the primacy of U.S. interests and the end of a period of unfair treatment of the U.S. in the world. The tone and intensity of debate, at least in the media so far, shows that this issue is a candidate to become a major fault line in U.S. politics and society, and a major factor that will shape voter behavior in the 2020 elections. The decision of some mayors in major cities and small-scale rallies that have taken place following the decision demonstrate the very quick potential mobilization of certain segments of U.S. society about this issue. Climate change has been a much politicized issue in the U.S. due to the polarization of politics about the existence of the phenomenon. After this decision, it will be debated more loudly by both sides. [Daily Sabah, June 3, 2017]