The solution is one that Washington has dodged for years: Let Mexican trucks use U.S. highways to deliver goods north of the border. U.S. foot-dragging - to please the Teamsters union, which fears competition - had yielded a pilot program that tested Mexican trucks for safety and pollution violations.

The checks gave passing grades to the foreign trucks, meaning it was time to follow through on the free-trade treaty, a prospect that opponents couldn't bear. So the truck inspections were canceled in the back pages of a giant omnibus spending bill passed by Congress and signed by President Obama.

Reaction was swift. Mexico has retaliated with tariffs on dozens of U.S. imports from potatoes to cell phones. The targets are calibrated to hit states with political leaders who might undo the damage. But, tellingly, Mexico stopped short of draconian options such as tariff on corn, a major import. Mexico's mad, but it's giving the United States another chance.

Washington is waking up to the trouble it's caused. Obama's team is huddling to study options. Another avenue is a visit this week by Secretary of State Hillary Rodham Clinton. Both Obama and Clinton have spoken against aspects of NAFTA, but killing the truck crossings without a full debate cheapens their arguments.

Clinton's trip is aimed at soothing anger in Mexico City over remarks by U.S. officials that Mexico is losing a vicious drug war that's left 7,000 dead in the past 15 months. Clinton may want to extend the conversation to fashion a better ending to the trucking dispute. It's an answer that Washington can easily offer: Let the trucks roll.