WASHINGTON - In his second big trip abroad since becoming U.S. president, Barack Obama arrives in Mexico on Thursday to show support for the Mexican government's efforts to fight a devastating drug war and boost security along the U.S. border.

Obama, who made his first foray onto the international stage in Europe earlier this month, will discuss energy and the economy with President Felipe Calderon in Mexico City before heading to Trinidad and Tobago for the Summit of the Americas on Friday.

White House officials played up the symbolism of the stop in Mexico, which is struggling to contain unprecedented criminal violence and combat a drugs war that is spilling over into the United States.

Denis McDonough, the Director of Strategic Communications at the White House's National Security Council, said Obama's visit underscored U.S. support for its southern neighbor at the highest levels.

It's designed to send a very clear signal to our friends in Mexico City that we have a series of shared challenges as it relates to the economy, as it relates to security, insecurity, the threat of violence, and the impact of drug trafficking on both our countries, he told reporters this week.

The Obama administration is tightening the U.S.-Mexico border to prevent trafficking of U.S. guns to Mexican cartels and is hoping to send Black Hawk helicopters to help Calderon defeat well-armed drug gangs that killed thousands last year.

Obama, a Democrat, hopes to improve relations with Mexico and other Latin American countries during his trip after a deterioration in relations that his advisers blame on Republican former President George W. Bush.

Obama's outreach to Mexico has already included a visit by Secretary of State Hillary Clinton, who soothed Mexicans by acknowledging the violence there stemmed partly from Americans' insatiable demand for drugs.

BORDER CZAR, ENERGY, ECONOMY

On Wednesday Homeland Security Secretary Janet Napolitano named a border czar, Alan Bersin, a former Justice Department official who had served in a similar role under former President Bill Clinton.

His ... sole mission is to make sure that all of the things happening with Mexico right now are happening in real time and producing the kinds of results that we anticipate, she told reporters at a news conference at the Mariposa port of entry.

Despite its resonance in the U.S.-Mexican relationship, the White House stressed that drugs would not be the only topic of discussion between the two presidents. Energy, trade and the economy would also feature.

Obama will likely echo the conclusions of a G20 summit in London this month with a promise to avoid protectionism -- a message Calderon is eager to hear. Mexico, a partner with Canada and the United States in the 1994 NAFTA trade pact, sends 80 percent of its exports to its northern neighbor.

Mexico slapped retaliatory tariffs on $2.4 billion worth of U.S. goods last month after Obama signed an omnibus spending bill that canceled a program allowing Mexican long-haul truckers to operate in the United States.

Obama will also meet with Mexican legislators during his visit before leaving on Friday for Trinidad and Tobago, where the fifth Summit of the Americas takes place.

Obama is expected to pledge to listen during the summit with hemispheric leaders as he tries to establish a cooperative new relationship with Latin America.

But the issue of Cuba is likely to test that quest for stronger ties. On Monday Obama lifted limits on family travel and money transfers to Cuba and let U.S. telecommunications firms start providing service for Cubans.

Leaders from the region, however, are expected to tell him those measures are not enough.

George W. Bush Hillary Clinton Energy Barack obama