A U.S.-Mexico border that's impossible to sneak across could devastate impoverished Mexican and Central American communities that depend on the millions of dollars that undocumented migrants send home to loved ones.

But those trying to slip into the United States say they aren't worried about President Bush's latest plan to help stem the tide of illegal immigrants — the deployment of 6,000 National Guard troops to the border.

The guardsmen could be deployed as early as next month, but will only provide surveillance and support to the Border Patrol, which would remain responsible for catching illegal immigrants.

CountryWatch: Mexico

More troops won't stop Antonio Urquieta from trying to cross the Rio Grande — again.

"They are only going to be supporting the Border Patrol. They won't be detaining anyone," said Urquieta, a 44-year-old carpenter from Chile who was hospitalized after falling from a railroad bridge while trying to sneak across the river.

Urquieta, who was recuperating at a shelter for immigrants waiting to jump the border in Nuevo Laredo, a sweaty city of 330,000 across from Laredo, Texas, said he would try to make it over the same bridge in coming days.

"If they catch me, I won't put up any fight," he said. "It will be the Border Patrol, not soldiers."

Experts say completely sealing the border is impossible.

"For decades, each president has increased police forces on the border and the number of migrants has increased, not declined," said Mexico City-based analyst Jorge Chabat. "A border that's closed completely? It's fantasy."

Still, Mexico says it will file lawsuits in U.S. courts if the National Guard arrests migrants, and its leaders worry that increased border surveillance will force crossers into more dangerous areas to avoid detection.

"I understand that sending 6,000 National Guard soldiers to the border is playing to internal pressures within the United States, but I want to express my complete rejection of this militarization," said Alvaro Elias, a member of President Vicente Fox's National Action Party and head of the executive committee in Mexico's lower House of Congress. "There's nothing else to call it."

Guatemalan Vice President Eduardo Stein said his country "deplores and rejects Washington's attitude."

"This is not the solution on the border," Stein said.

Waiting outside the Nuevo Laredo migrant shelter, 23-year-old Nicaraguan Isacio Bellorin said he and thousands of others won't be deterred.

"You just have to be more creative crossing," he said. "Necessity ensures people will find a way."

The oldest of five boys, Bellorin said he decided to head north after his father's death left the family with no means of income. He said that a U.S. border completely closed to illegals would hit the poor the hardest.

"Our families, the economies of our countries, depend on migration. A lot of poor people would suffer the consequences," he said. "In Mexico, it would be bad. But Central America has even fewer options."

Victor Clark, a border expert in Tijuana, said a border truly sealed to illegal immigrants would also send economic shock waves through the United States, where employers rely on undocumented laborers to keep prices low.

"The message was not for Mexico. It was for American citizens who want to feel safe and secure about the border," Clarke said of Bush's speech.

Chabat said Bush was simply prodding the Senate — which is weighing comprehensive immigration reform — with the plan to send soldiers to the border.

"The proposal isn't about reducing immigration," he said. "It's about winning Republican votes in Congress."

Trinidad Hernandez, a 38-year-old from Honduras who said he planned to swim across the Rio Grande and join his three brothers working construction in Virginia, said "the country is not ours, it's the Americans."

"They can do what they want," he said. "But we are going to keep trying to cross."