Bogota, Sept. 28 -- The United States' cancellation of Colombian President Gustavo Petro's entry visa set off the sharpest rupture in years between Washington and Bogota, converting a long, often pragmatic partnership into an open argument over protest speech, the Gaza war, and the reach of American immigration powers. The immediate spark was a street-side appearance in New York, where Mr. Petro addressed pro-Palestinian demonstrators outside the United Nations and challenged the moral standing of U.S. policy. Within hours, officials in Washington moved to pull his visa, a step that jolted both capitals and left diplomats tallying the fallout while the political theater continued on the sidewalk and online. For a baseline of the sequence ...