The United States and its Latin American allies launched last month a renewed diplomatic offensive against the regime of Venezuela’s Nicolás Maduro, which more than 50 democracies around the world deem illegitimate. It began on Sept. 23 with a meeting between the United States and more than a dozen Latin American parties to the Inter-American Treaty of Reciprocal Assistance, during which they agreed to investigate and arrest Maduro regime officials and others suspected of drug trafficking, money laundering, and financing terrorism. It escalated that Friday when a score of diplomats walked out in protest during Maduro’s Vice President Delcy Rodríguez’s speech at the United Nations General Assembly.

But the most concerning moment for the future direction of the Venezuela crisis came when Colombian President Iván Duque took to the U.N. podium to denounce the Maduro regime for providing support to illegal armed groups from Colombia. “My government has irrefutable and conclusive proof that corroborates the support of the dictatorship for criminal and narcoterrorist groups that operate in Venezuela to try and attack Colombia,” he said, holding up a copy of a 128-page dossier. He pledged to turn over the evidence to the secretary-general of the U.N.

Maduro is playing a dangerous game on the Colombian border. His actions could provoke armed conflict—or allow an unplanned confrontation to spiral out of control.

Venezuela’s support for Colombian guerrillas and narcotraffickers is nothing new. But the issue has taken on an added urgency in recent weeks after two leading members of the largely demobilized Revolutionary Armed Forces of Colombia (FARC)—Jesús Santrich and Iván Márquez, who the United States says were still dealing in drugs in violation of the 2016 peace agreement—disappeared, only to resurface in a video declaring a new chapter in their war against the Colombian state. Colombian authorities say the video was filmed in Venezuela.