Leaders from the United States, Mexico, and Canada have pledged to work together to combat the spread of the H1N1 swine flu and address climate change, although they have differing views on trade disputes at their "three amigos" summit. US President Barack Obama, Mexican President Felipe Calderon, and Canadian Prime Minister Stephen Harper met amid economic challenges in each of their countries, with a US recovery being crucial for regional progress. Obama and Harper announced plans to exchange information in anticipation of a potential increase in the H1N1 virus in the upcoming months. Calderon expressed the importance of all three countries preparing responsibly for the return of the virus and minimizing its impact on their populations. All three leaders pledged to uphold the North American Free Trade Agreement that connects their countries in trade, but they had differing opinions on certain issues. Harper brought up Canada's concerns about the "Buy American" provisions in the U.S. economic stimulus plan with Obama, which Canadian companies fear could exclude them. Canada is the largest trading partner of the United States. Obama emphasized that no extensive protectionist measures have been implemented and that the "Buy American" provisions only apply to the stimulus and do not jeopardize the billions of dollars in trade between the two countries. Calderon, who is working to convince Obama to resolve a cross-border trucking dispute to allow Mexican trucks to enter the United States, stated that all three leaders agree on the importance of following NAFTA and addressing unresolved issues that hinder regional competitiveness. Obama informed Calderon that he was collaborating with the US Congress to address safety issues related to Mexican trucks. He emphasized the importance of avoiding protectionism and expanding trade among the United States, Mexico, and Canada. The leaders also released a statement expressing their commitment to combating climate change leading up to the global summit in Copenhagen. They stressed the importance of taking aggressive action on this issue.