US Secretary of State Mike Pompeo met in Washington on Friday with his South Korean counterpart Kang Kyung-wha to help prepare for the landmark June 12 summit between US President Donald Trump and North Korean Supreme Leader Kim Jong-Un. With positive mood music now surrounding the Trump-Kim session, and the US president’s earlier May 22 summit with South Korean President Moon Jae-in, the Korean peninsula offers the potential to become the US president’s first big foreign policy win. Any final, comprehensive deal between Washington and Pyongyang is possibly years away. Yet, it is already clear that it would be a remarkable achievement if Trump were to help preside over denuclearization of the Korean continent; help seal a peace treaty between North and South to supplement the armistice ending the 1950-53 Korea War; and in the process de-escalate tensions in the world’s last Cold War-era frontier. Should Kim ultimately decide to abandon North Korea’s nuclear program in exchange for economic aid and security guarantees, the reason why this would – potentially – be so central to Trump’s eventual foreign policy legacy is that almost a year and a half into office, the president’s international actions have been much more defined by the dismantling of policies of previous presidents, especially Barack Obama, rather than building something new. He has, for instance, this week withdrew US participation from the nuclear agreement between Iran and the United States, China, Russia, the United Kingdom, France and Germany. Prior to that decision he scrapped US involvement in the Trans-Pacific Partnership (TPP) trade deal with key allies in Asia-Pacific and the Americas; withdrew Washington from the Paris climate change deal agreed by over 170 nations; and launched a review of the North America Free Trade Agreement, which may yet collapse in 2018. The first three of these initiatives (Iran, TPP and Paris) were Obama-era signature policies, and Trump has also partially rolled back other key measures from the previous administration, including the Cuba liberalization policy. “The president’s international actions have been much more defined by the dismantling of policies of previous presidents, especially Barack Obama, rather than building something new.” Andrew Hammond Yet, for all this diplomatic action, thus far the new administration has failed to forge any clear, coherent and comprehensive new Trump doctrine, centered around his “America first” vision. When Trump moved into the White House, he promised a radical platform that could have reshaped US foreign and trade policy more radically than at any point since the beginning of the Cold War, the time that Harry Truman helped build a consensus around US global leadership. To be sure, Trump has made some moves to shift away from this post-war orthodoxy – pursued by both Democratic and Republican presidents – such as building US-led alliances to expand the liberal democratic order. But in practice, much of the last year and a half has also been characterized by policy incoherence and U-turns on issues such as military action in Syria, a departure from Trump’s 2016 campaign rhetoric; and whether key international alliances like NATO are “obsolete” or “not obsolete.” These flip-flops reflect not just the ad-hoc nature of the new president’s style of governing, and his contrarian character, but also the divisions within his team on key foreign policy issues. Take the example of the Paris climate deal, the Iran nuclear agreement and TPP, where then-secretary of state Rex Tillerson was just one of the senior members of his team urging Trump to remain in the accords rather than leaving them. Yet, as the president enters mid-2018, he now appears to have in place a foreign policy personnel much more aligned to his political instincts. Former CIA director Pompeo has replaced Tillerson as secretary of state, and the conservative hawk John Bolton has taken over as national security adviser from the more pragmatic General H.R. McMaster. This changing of the guard could be very important to Trump, almost 18 months into office, in the context of the fact that his political window of opportunity to put an enduring stamp on US foreign policy may soon narrow rapidly, unless he wins a second term in 2020. With this in mind, he and his new team will now seek to double down on other foreign policy priorities. These include the ambition to do the “deal of the century” in the Middle East with Israel and the Palestinians, which will become more complicated by the US president’s decision to move the US Embassy this week to Jerusalem; and forging renegotiated economic relationships with key countries like Japan and China, which are seen by the president as less one-sided and detrimental to the United States. It is also to be hoped that Trump’s new team will prove better foils than Tillerson and McMaster were for the president’s ad hoc style of governing, which regularly exposes lack of experience and knowledge of international issues. If so, this will help serve as a compass for the White House in helping to navigate the significant uncertainties of international affairs in 2018 and beyond. Taken overall, the historic potential opportunity offered by the Korea negotiations could become a central part of Trump’s foreign policy legacy. However, in this high-stakes gamble for glory, the president could yet emulate many others who have failed to bring a sustained, peaceful diplomatic outcome to one of the key international challenges facing the United States. Andrew Hammond is an associate at LSE IDEAS at the London School of Economics.