PHOENIX — Arizona National Guard troops will arrive at the U.S. border by the end of the month.

Lt. Valentine Castillo said the first batch of soldiers began their training on Monday with Customs and Border Protection to be members of “entry identification teams.” These soldiers will watch the border area for unusual activity and report what they find to federal agents.

He figures the first batch of soldiers going through the training will be ready to take their posts by Aug. 31.

Castillo would not provide specific numbers. But he said a new batch of soldiers will begin their training this coming Monday, with successive multi-day classes each week until everyone within the program is ready.

That, he estimated, would happen by Oct. 1.

Castillo said while the soldiers will be armed, their mission is not to confront illegal immigrants. Instead, he said, they are simply supposed to radio what they find to Border Patrol officials, who will pursue the crossers.

An order signed by the president authorizes Arizona to activate up to 524 members of the Guard, at federal expense, to help along the border. Castillo said a majority of these will be part of entry identification teams.

A smaller, unidentified number will be working with Immigration and Customs Enforcement to analyze intelligence data to look for criminal patterns. Castillo said their training has not yet begun.

The Arizona soldiers are the largest contingent of 1,200 troops that Obama authorized in May to be placed on active duty at federal expense for up to a year, through June 30. The president arranged to have the cost, up to $135 million, split between the Department of Defense and the Department of Homeland Security.

But actual deployment has been delayed for what Guard officials have called a “ramping up” period, first of seeking volunteers and screening them and, now, for training.

Jack Harrison, public affairs director of the National Guard Bureau, said there will be a “ramp down” prior to June 30.