The department is concerned enough about the escalating violence on the southwest border that its plans to respond to the situation includes -- as a last resort -- deploying military personnel and equipment to the region if Homeland Security Department agencies should be overwhelmed, said Roger Rufe, the department's head of operations.

However, Rufe, echoing comments a day earlier from President Barack Obama, said now is not the time to militarize the southwestern border with Mexico despite drug violence just inside Mexico that threatens to migrate across the border.

"We would take all resources short of DoD and National Guard troops before we reach that tipping point," Rufe told lawmakers. "We very much do not want to militarize our border." DoD is the Department of Defense.

Rufe said military forces would be called in only when homeland security and other government agencies could not handle the problem. He did not specify what circumstances would trigger a call for troops.

The Mexican government has deployed 700 extra federal police to Juarez, where local police had been swamped by drug violence. This month, 3,200 federal troops were sent to the city.

Mexican officials say the violence killed 6,290 people last year and more than 1,000 in the first eight weeks of 2009. Warring drug cartels are blamed for more than 560 kidnappings in Phoenix in 2007 and the first half of 2008, as well as killings in Atlanta, Georgia, and Birmingham, Ala.

Rufe said that while the violence along the border in Mexico is appalling, violent crimes have not increased in U.S. border cities as a result. He said kidnappings are up, but violent crime is down.

"We're not so concerned, at least at this point, about that violence spilling over into our cities," he said.

Further, the Homeland Security Department's representative in Mexico, Alonzo Pena, said the violence there is not as dangerous to U.S. tourists as has been portrayed.

Pena said the violence is in isolated areas of the country and affects only the people involved in criminal activity. He said the violence is not affecting U.S. citizens visiting Mexico, and Americans should not cancel their vacations in the country.

This month, the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives warned college students on spring breaks not to travel to parts of northern Mexico because it was too dangerous.

In February, the State Department advised travelers to avoid areas of prostitution and drug-dealing in Mexico.