Following a historic election victory in June, Colombia’s first ever leftist president, Gustavo Petro, assumed office Sunday before a crowd of hundreds of thousands. He pledged to “bring to Colombia what it has not had for centuries, which is tranquility and peace.” Having campaigned on a radical agenda to redistribute wealth, end the war on drugs and tackle the climate crisis, Petro is looking to break with the country’s conservative politics. But the new leader has the potential not only to transform the political landscape of Colombia, but to accelerate the decline of U.S.