National Guard troops assigned to the Southwest border will begin to arrive Aug. 1, and the federal government is sending other reinforcements to stem the flow of illegal immigrants and narcotics entering the state, Homeland Security Secretary Janet Napolitano said Monday."These troops will provide direct support to federal law enforcement officers and agents working in high-risk areas to disrupt criminal organizations seeking to move people and goods illegally across the Southwest border," Napolitano said.

In this 2007 file photo, a National Guard unit patrols at the Arizona-Mexico border in Sasabe, Ariz. (AP)

In addition, Napolitano said, hundreds more Border Patrol agents and Customs officers are being moved to the Southwest to prowl the deserts and operate inspection stations. She said Immigration and Customs Enforcement will open an office in Ajo, Ariz., and the Department of Homeland Security is sending a new team to Douglas, Ariz.

"We are also reassigning major technology assets, including mobile surveillance systems, thermal-imaging binocular units, and trucks equipped with detection scopes, as well as observation and utility aircraft," Napolitano wrote in a column published Monday in The Arizona Republic.

This spring, the Obama administration announced its plan to deploy the National Guard soldiers. During a meeting with Republican Gov. Jan Brewer in June, administration officials said up to 1,200 troops would be assigned, with 524 operating in Arizona. The Department of Homeland Security said the other troops will be stationed in Texas (250), California (224) and New Mexico (72).

The beefed-up enforcement comes as Arizona implements a controversial new immigration law that is under assault in federal court on constitutionality grounds. The law, set to take effect July 29, makes it a state crime to be in the country illegally. Napolitano's announcement also comes amid statewide political campaigns dominated by immigration-related issues, as both Democratic and Republican leaders complain about Arizona's status as a smuggling corridor.

Gov. Brewer, Republican Sens. John McCain and Jon Kyl, and Democratic Rep. Gabrielle Giffords have been among the outspoken elected officials clamoring for heightened enforcement.

McCain and Kyl called Monday's announcement "a step in the right direction" in a joint news release, but added, "A lot more needs to be done."

Giffords said, "It should not have taken this long to have the troops dispatched to the border area."

Brewer called the news of more resources "welcomed," but said "it does not appear to be enough, or tied to a strategy to comprehensively defeat the increasingly violent drug and alien smuggling cartels that operate in Arizona on a daily basis."

Napolitano repeated previous assertions that the U.S.-Mexican border has become more secure, not less, in the past few years.

"Last year, illegal crossings along the Southwest border were down 23%. ... And, by all measurable standards, crime levels in U.S. border towns have remained flat for most of the last decade."

Napolitano conceded that the Tucson sector, which covers most of Arizona's southern flank, is a funnel point for human and drug smuggling because of heightened enforcement elsewhere.