In what should come as a surprise to no one, Gov. Rick Perry said Monday he will send up to 1,000 National Guard troops to the Texas border to bolster the response to the flood of Central American migrants into the U.S.Perry said it is not the recent headline-grabbing influx of unaccompanied minors that prompted his move. Speaking in Austin, the governor told reporters that these migrant children make up only 20 percent of the total apprehensions on the border.But detaining and caring for the deluge of kids has taken an inordinate amount of the Border Patrol’s time and resources, both of which should be spent on the agency’s primary mission of catching criminals crossing the border. Criminals, said the governor, are exploiting gaps in enforcement while border agents are distracted.Last month, Perry and state leaders announced they would spend $1.3 million a week for a surge of Department of Public Safety officers on the border.Perry credited a recent decline in apprehensions (36 percent in three weeks), to the DPS surge.Under his new plan, National Guard troops would supplement the efforts of DPS personnel, enhancing security and providing a visible presence along the border.There are problems with Perry’s approach. For example, National Guard troops are not authorized to make arrests. They can only direct immigrants to the proper authorities — “refer and deter,” as Texas National Guard Major General John Nichols put it. Further, it’s unclear whether the ramped-up DPS presence is responsible for the dip in illegal migrants. U.S. diplomatic efforts aimed at preventing kids from fleeing their homelands in the first place may be having some effect on would-be travelers.And the volume and intensity of media coverage on the topic — which has surely filtered back to Central America — is probably a deterrent force in its own right. In ordering troops to the border, Perry is thumbing his nose at the president. He’s also getting ahead of members of his own party, including Rep. Kay Granger of Fort Worth, whose special House working group is expected to call on the president to mobilize the National Guard in recommendations due out this week.Perry’s move also comes with a high cost to Texans — $12 million a month — and no guarantee that the federal government will reimburse the state.But absent any federal action — approval of the president’s $3.7 billion supplemental funding request, passage of a bill like the Cornyn-Cuellar HUMANE Act — Perry is limited in his ability to address a serious and growing problem in his own state.Sending troops to the border is not the ultimate answer on immigration, but it’s not unprecedented. President George W. Bush did it in 2006 and President Barack Obama did it in 2010. Perry has addressed the “seal the border” part of the immigration debate. Congress must get busy on resolving the rest.