Latin American leaders gathered over the weekend in scenic Trinidad and Tobago for the Summit of the Americas. Thirty-four countries in the Western Hemisphere were represented, including the United States, but Cuba was notably absent.

The worldwide recession is wreaking havoc across the vast region, where countries already were struggling before the global collapse.

The Caribbean setting was deceptively tranquil, given the chaos that reigns elsewhere in Latin America. At center stage is Mexico, where drug-related violence has claimed 9,000 lives since December 2006, when Mexican President Felipe Calderon took office and aggressively moved to combat powerful, now-warring drug cartels.

President Barack Obama on Thursday made the first presidential visit to Los Pinos, the picturesque White House in Mexico City, since President Bill Clinton visited 12 years ago. Obama has met with Calderon twice within his first 100 days in office and made one of only a few U.S. presidential trips to Mexico over the last century.

Such attention from a U.S. president is of huge symbolic importance south of the border. Obama drew huge crowds in Mexico City and vast television audiences throughout Latin America. Millions watched Obama and Calderon's post-summit press conference.

Calderon doesn't have the flair of Vicente Fox, his loquacious, boot-wearing predecessor. But he quickly established himself as a fearless foe of drug lords and public corruption. His decision to fight the drug traffickers head-on provoked the ongoing bloodshed.

Calderon is serving the final four years of the Mexican president's sexenio — six-year term — which prohibits re-election. Those years coincide with Obama's term, which ends in 2012. There is an opportunity for watershed developments between the neighbors.

Both presidents grasp the immediate urgency of restoring social order while also working on initiatives to propel their nations through extraordinarily hard economic times.

They are not aligned on all issues. Mexico wants a U.S. ban on assault weapons, the preferred weapon of drug assassins, and the lifting of the U.S. trade embargo against Cuba. Last week, Obama signaled that he wasn't ready to renew congressional battles on assault weapons and took only a modest first step toward normalizing relations with Cuba.

More serious business remains: environmental concerns, clean energy, climate change, improved infrastructure along trade routes and reform of U.S. immigration policy.

The first priority is restoring the Mexican rule of law. The United States must agree to an inter-American gun treaty to help quell the drug violence that paralyzes Mexican cities like Ciudad Juarez and spills over into neighboring El Paso, Texas.

Last week, Homeland Security Secretary Janet Napolitano announced that the United States would send more federal support to the border to combat illegal drugs, gun smuggling and illegal immigration. She also announced the creation of a "border czar."

Calderon spoke in terms of "a new era," "trust and respect" and "a generation of change." Standing on Mexican soil, Obama took responsibility for Americans' huge consumption of illegal drugs and complicity in arms smuggling into Mexico.

Latin American leaders historically have felt either lectured or neglected by the United States. Obama has established a new tone of good will and a willingness to enter full partnerships. That willingness now must be sealed with action.

REPRINTED FROM THE ST. LOUIS POST-DISPATCH.