Along with other responsibilities, President Barack Obama is assuming control of the decades-long struggle to stop illegal drug shipments into the United States from Latin America and elsewhere. 

With drug-related violence soaring in Mexico, the issue is gaining new urgency at the same time U.S. anti-drug cooperation with some Latin American nations is strained because of political differences. 

Drug-sniffing canines are the first line of defense against cocaine smuggling at Quito's main airport. Officials say Colombian-based drug traffickers are seeking new routes to smuggle packages into the United States.

Police lieutenant Ivan Ayala says more than 160 kilograms of illicit drugs were intercepted by dogs at the airport last year. Only days earlier a young Estonian woman was caught with a suitcase packed with cocaine. 

"There are many ways to hide it," Ayala said. "Some smugglers use the panels of a suitcase. Others do not try to hide it, they just pack it in a suitcase with clothing."

Officials say smugglers have grown more creative in recent years, as anti-drug efforts have increased. Aggressive measures in Colombia have pushed traffickers across the border into Ecuador and other neighboring countries.

In response, the United States has expanded support for anti-drug measures in Ecuador, including training some 60 new canine teams.

"Another main part of our program is with the Ecuadorian military on the northern border, near Colombia," explained John Haynes, who directs the anti-narcotics section at the U.S. Embassy in Quito.

U.S. officials say Ecuador is a valuable partner in the drug fight. But President Rafael Correa plans to end one cooperation deal. He says he will not renew a lease that ends this year for an airbase used by U.S. drug surveillance flights.

Eduardo Gamarra of Florida International University says those flights cover major transit routes into the United States. 

"I think they will need them to monitor the whole western coast of South America," he said. "But are they essential? Probably not, given technology."

He says the dispute in Ecuador may not pose a crisis for President Obama. But it is not the only problem facing the new president. Leftist leaders in Venezuela and Bolivia have been fierce critics of the Bush administration, and they have discontinued anti-drug programs with the United States in recent years.

Colombia's government is facing criticism about human rights violations in its long-running battle with drug gangs and leftist rebels involved in the drug trade. The U.S. has spent billions to help fight drug trafficking in Colombia, the world's top cocaine producer.

During the presidential campaign, Mr. Obama expressed concerns about human rights abuses in Colombia. But FIU's Gamarra says the concerns are unlikely to upset the U.S. partnership with Colombia advanced by former President Bush. 

"I don't think the Obama administration will abandon the drug effort," he said. "All that entails, is a full-scale development effort."

But it is Mexico's worsening drug-related violence that is likely to pose the most urgent issue for the new president in the war on drugs. Violence linked to drug gangs killed more than 5,000 people last year. And Mexican officials want the U.S. to do more to stop guns coming across the border into Mexico.  

Earlier this month, Mexico's President Felipe Calderon was in Washington for talks with Mr. Bush and Mr. Obama. Mr. Bush expressed hope that cooperation continues in years to come.

"The less drugs we use, the less pressure there will be in Mexico," he said. "We have got responsibilities to help prevent guns from going from the United States into Mexico."

Attacks on Mexican police have raised fears that security forces will take aggressive action to retaliate. FIU's Gamarra says Mr. Obama may be called on to work with Mexico to prevent such abuses.

"They [Obama administration officials] are going to stress concern over human rights, but I think increasingly we are going to see the kind of repression we saw in Colombia in Mexico," he said.

He says the Obama administration may be able to press both governments to improve their human rights records. Whether the new administration can also curtail drug shipments may prove to be a more difficult task.