U.S. takes hard line as NAFTA talks kick offAug. 16
NAFTA negotiators aim for 'ambitious' start to talksAug. 15
Negotiators from Canada, Mexico and the United States are aiming for an "ambitious" first round of trade talks, a senior U.S. official said on Tuesday, as the countries try to fast-track a deal to modernize the 23-year-old pact by early next year.