Updated

The first wave of about 800 National Guard soldiers will head to the U.S-Mexico border next week, including planners and leadership personnel who will stay longer than the planned 21-day missions, the National Guard chief told lawmakers Wednesday.

Lt. Gen. Steven Blum said 200 soldiers are preparing to go to each of the four border states — California, Texas, Arizona and New Mexico — around June 1. He said the initial troops will be part of a longer-term force of project managers who will stay on the job over time to provide continuity in the new border program.

The troops represent the launch of President Bush's plan to dispatch up to 6,000 National Guard members to states bordering Mexico to support the Border Patrol and help stem the flow of illegal immigrants across the border.

It was not clear whether the initial influx of Guard members would come from the four border states or from other units across the country. Blum said the Guard troop that will be deployed longer than three weeks are volunteers.

Under the plan, most of the troops would spend about 21 days, which includes their normal annual two-week training mission, working along the border. The Guard troops would be used for engineering, road and fence building, transportation, logistics and surveillance and reconnaissance.

Blum and Paul McHale, assistant defense secretary for homeland defense, repeatedly told members of the House Armed Services Committee that the guard members would be armed for personal protection, but would not do significant law enforcement duties.

And they said the two-year plan — which calls for using up to 6,000 troops at a time in the first year, and no more than 3,000 in the second year — will not overtax the guard or impair troops' ability to train or prepare for combat.

Some committee members echoed complaints from critics who have suggested that the border plan would overburden a National Guard that is already stretched by deployments to Iraq and Afghanistan. But Blum said the border program, coupled with the approximately 71,000 Guard members deployed overseas, still leaves more than 350,000 Army and Air Guard available for other homeland defense or disaster assistance.

David Aguilar, chief of the border patrol, also told lawmakers that the plan will be augmented with additional, strategically located fencing, as well as an increased of about 6,000 border patrol guards by some time in 2008.

Congress members, including committee Chairman Rep. Duncan Hunter, R-Calif., urged officials to use more fencing to stop the flow of illegal immigrants.