President Barack Obama, Canadian Prime Minister Stephen Harper and Mexican President Felipe Calderón are in Guadalajara, Mexico, today for the North American Leaders’ Summit. They will discuss, among other topics, what to do about the explosion in drug-trafficking violence on the continent. But they are also expected to address the political situation in Honduras.

Too bad the Colombian ministry of defense will not also be on hand. It could show them evidence of the connection between the Honduran supporters of deposed Honduran president Manuel Zelaya and the most important South American supplier of illegal drugs to North America—the Revolutionary Armed Forces of Colombia (FARC). I know this because recently that evidence landed on my desk.

The FARC is a major player in the cocaine trade, and documents found in computers captured by the Colombian military in a raid last year on a FARC camp in Ecuador show that the rebels have been active in Honduras. A number of those documents came into my possession last week. One is a March 2005 letter to the now-deceased rebel leader Raúl Reyes from another FARC honcho. It provides a list of “political contacts” that have been established around the region and in Spain to provide “support” and help “coordinate the work” of the FARC.

Honduras’s Partido de Unificación Democrática (UD) is on the list. The party has only a small representation in Congress, but it is the only political party that supports the return of Mr. Zelaya. Wherever there are violent demonstrations and roadblocks advocating for Mr. Zelaya, the UD is there.

The FARC letter says there are 45 such organizations. Also included, Mr. Calderón might be interested to know, is Mexico’s Workers’ Party and the Communist Youth of Mexico.

The UD-FARC relationship aside, Mr. Zelaya broke Honduran law by trying to change the constitution so he could run for re-election. He also incited a mob that broke into an Air Force warehouse where ballots for his illegal referendum were stored. On June 28, he was arrested by order of the Supreme Court, deported by the military and removed from office by Congress. Even his own Liberal Party favored kicking him out of office and out of the country, and a majority of the population backs those decisions.

Messrs. Obama and Calderón, however, do not. They both want Mr. Zelaya reinstated.

Two weeks ago the Obama administration turned up the heat on Honduras by pulling the visas of some of its government officials. Not to be outdone, Mr. Calderón rolled out the red carpet last week in Mexico City for Mr. Zelaya in a high-profile show of support for his return to power. To its credit, Mr. Harper’s government has been more measured in its response to the events in Tegucigalpa.

It is said that a Mexican president who gets to the right of the White House touches the third rail of that country’s domestic politics. That might explain why the center-right Mr. Calderón decided to host a state visit for Mr. Zelaya. He wants to stay left of a leftist American president on this issue.

But it’s not that simple. Mr. Calderón has been waging a “war” on drug cartels in Mexico that has cost the lives of 1,077 law-enforcement agents since December 2006. Now both he and Mr. Obama are going to have to explain their support for a political faction in Honduras that is allied with organized crime. According to the evidence collected by Colombian intelligence that came to me indirectly, that’s exactly what they are doing.

Hondurans don’t want Mr. Zelaya in their country because he leads a violent, antidemocratic mob, and he tried to use it to undermine the country’s institutions in exactly the same way that Venezuela’s Hugo Chávez has done. Mr. Chávez has also coached Nicaragua’s Daniel Ortega, Ecuador’s Rafael Correa and Bolivia’s Evo Morales. Those democracies, too, have been seriously compromised.

But even if Messrs. Obama and Calderón don’t care about the freedom of Hondurans, they can’t ignore the likelihood that the establishment of a chavista government in Honduras would raise the cost, in blood and treasure, of their war on drugs.

The FARC connection could go a long way in explaining why Mr. Chávez is pushing so hard for Mr. Zelaya to be restored to power. It is already well established that the Venezuelan strongman actively supports the FARC in South America. Rebels have a safe haven across his border and just last month a Colombian army raid on a FARC camp yielded a cache of Swedish-made anti-tank rocket launchers that originally had been sold to Venezuela. Mr. Chávez has still not come up with a credible explanation of how the Colombian terrorists got hold of them.

A July report from the U.S. General Accountability Office found that Venezuela has become a major transit route for Colombian cocaine, 60% of which is exported by the FARC. The GAO also found that high-ranking members of Mr. Chávez’s government and the Venezuelan military are accomplices. “According to U.S. officials, corruption within the Venezuelan National Guard poses the most significant threat because the Guard reports directly to President Chávez and controls Venezuela’s airports, borders, and ports,” the GAO said.

The leaders at the summit today are going to talk about their war on drugs. Perhaps Mr. Calderón and Mr. Obama will tell us why they are backing an ousted Honduran politician whose supporters make common cause with drug-trafficking terrorists. All North Americans deserve an explanation.