Leaders of the United States, Mexico, and Canada, known as "the three amigos," have gathered in Mexico for a summit to discuss trade issues and the threat of drug gangs. President Barack Obama, Canadian Prime Minister Stephen Harper, and Mexican President Felipe Calderon will have dinner on Sunday night followed by talks on Monday. The main topics of discussion include how to boost their economies, ensure smooth trade, and address the issue of Mexican drug gangs dominating the drug trade along the U.S. border and into Canada. It is unlikely that major agreements will be announced during the summit, with Obama's national security adviser, Jim Jones, expecting it to be a step in an ongoing dialogue that will eventually lead to agreements. Calderon is expected to pressure Obama to resolve a cross-border trucking dispute. According to the North American Free Trade Agreement, Mexican trucks should be allowed to enter the United States, but American trucking companies argue that Mexican trucks are unsafe. This issue has been ongoing for years and led to Mexico imposing retaliatory tariffs of $2.4 billion on U.S. goods in response to a bill signed by Obama that canceled a program allowing Mexican trucks to operate outside the U.S. border zone. U.S. business groups have been urging the White House to resolve the dispute, as they believe the ban could result in the loss of thousands of American jobs. Mexico's ambassador to the United States, Arturo Sarukhan, expressed the desire for a final resolution to the trucking issue. He expressed his desire to reach an agreement by the end of the year. Michael Froman, a top White House official, informed reporters that the Obama administration is actively addressing the issue and working with Congress to address safety concerns. Canadian officials are concerned about the "Buy American" components of a $787 billion economic stimulus package that could potentially exclude Canadian companies from U.S. construction contracts funded by the stimulus. Canada, being the largest trading partner of the United States, is expected to discuss these concerns. Froman mentioned that the administration is in talks with Canada and other countries to implement the "Buy American" provision in a manner that complies with the law and international obligations, while minimizing trade disruptions. Obama addressed concerns about potentially reopening the NAFTA treaty unilaterally, stating that now is not the time to add enforceable labor and environmental protections due to the weakened economies of the three nations involved. He expressed interest in improving the treaty but emphasized that the focus should be on the current economic situation. Another key issue at the summit is addressing the violence caused by Mexican drug gangs, despite President Calderon's efforts to combat them over the past three years. The death rate from this violence has increased significantly since 2008, with Mexican traffickers being blamed for crime as far north as Vancouver. Obama is supporting Calderon's actions, stating that he is doing the right thing by targeting drug cartels with courage. Obama assured Calderon of full support during a visit in April, but Mexico is concerned about the delay in receiving anti-drug equipment and training. The leaders plan to discuss H1N1 swine flu and climate change at the summit in preparation for international talks in Copenhagen in December.