LAREDO, Texas (AP) September 8, 2005 - A Mexican army convoy crossed into the United States on Thursday to bring aid to hurricane victims, becoming the first Mexican military unit to operate on U.S. soil since 1846.

The 45-vehicle convoy was carrying water treatment plants and mobile kitchens to San Antonio, where the soldiers apparently planned to feed and provide other help for evacuees from the New Orleans area.

The first green trucks, with Mexican flags attached to the sides, crossed the international bridge at Laredo at about 8:15 a.m.

The Mexican government was already planning another 12-vehicle aid convoy for this week. It has sent a Mexican navy ship toward the Mississippi coast with rescue vehicles and helicopters.

Radio talk shows and newspapers in Mexico buzzed with excitement over news that this country, long on the receiving end of U.S. disaster relief, was sending a hurricane aid convoy north.

The mayor of New Orleans has said thousands may have died from Hurricane Katrina, which struck the U.S. Gulf of Mexico coast Aug. 29. Hundreds of thousands have been displaced.

‘High symbolic content’

Mexico has sent disaster relief aid missions to other Latin American nations, but not to the United States. In 1846, Mexican troops briefly advanced just north of the Rio Grande in Texas, which had then recently joined the United States.

Mexico, however, did not then recognize the Rio Grande as the U.S. border. The two countries quickly became mired in the Mexican-American War, which led to the loss of half of Mexico's territory in 1848.

The convoy has “a very high symbolic content,” said Javier Oliva, a political scientist at Mexico’s National Autonomous University. “This is a very sensitive subject, for historic and political reasons.”

Large Mexican flags were taped to many of the 35 olive-green Mexican Army trucks and tractor trailers as they rumbled northward toward the border Wednesday.

The convoy includes two mobile kitchens that can feed 7,000 people a day, three flatbed trucks carrying mobile water-treatment plants and 15 trailers of bottled water, blankets and applesauce. The 195 Mexicans taking part include military engineers, doctors and nurses.

“This is the first time that the United States has accepted a military mission from Mexico” for such work, said Javier Ibarrola, a newspaper columnist who covers military affairs in Mexico.

The relief mission was controversial for some Mexican lawmakers, who said the president should have sought Senate approval before sending troops abroad. But the administration of President Vicente Fox said no such approval was needed for aid missions. But it nevertheless later asked permission and the Senate approved it.