WASHINGTON -- Two other U.S. presidents have deployed National Guard troops to the southern border since 2006, out of security concerns.
In Operation Jump Start, President George W. Bush federalized 6,000 National Guard troops in California, Arizona, New Mexico and Texas. Despite the presence of armed U.S. soldiers and airmen, their mission was mostly passive, Customs and Border Patrol said. Across the border in Mexico, another battle was simmering as Mexican officials declared war on drug cartels in late 2006, sparking waves of killings and instability that threatened spillover.
Laws known as "Posse Comitatus" forbid using the military for domestic law enforcement outside military bases, leaving troops focused on conducting surveillance from ground stations and helicopters, installing fences and vehicle barriers and training.
Troops were typically expected to avoid capturing suspected drug traffickers or illegal aliens and, instead, report activity to federal agents, but orders that activate troops to the border affected what military personnel could do.
Under Title 10, for instance, Guard troops are under the command of the secretary of defense, using federal funds. Troops activated under Title 32 are federally funded but are under the command of the state governor, where they have more flexibility for law enforcement operations.
Officials said at the time that it was a necessary augmentation that allowed agents to pivot from administrative and infrastructure tasks and focus on ground operations.
But the $1.2 billion price tag raised questions about the use of troops to fulfill a Department of Homeland Security mission, as National Guard troops were exhausted from rotations in Iraq and Afghanistan.
There were also tensions on the border after a deadly 1997 incident involving the military. A U.S. Marine shot and killed an American high school student carrying a .22 rifle who was mistaken for a hostile person as he herded goats at the Texas border, leading to a temporary halt of military activity there.
Homeland Security pointed to some successes, including large drug seizures and an incident in which Guard troops dove into the Rio Grande to save a Central American migrant from drowning.
The successor to Jump Start, Operation Phalanx, began in 2010 with authorization from President Barack Obama to deploy 1,200 troops along the border, again amid fears that violence would spread on the U.S. side after some high-profile killings north of the border, The Washington Post reported in 2011.
Another reason: Customs and Border Protection agents needed time to fill their ranks after staffing shortfalls.
National Guard troops deployed a fleet of UH-72 Lakota helicopters later in the mission with infrared camera arrays to detect movement from the sky at night and through some of the foliage migrants use as concealment.
A release from the Guard said the helicopters typically included a Border Patrol agent on board. The Lakotas used powerful radio equipment that helped agents communicate with one another, and Guard units spread over vast areas.
The Guard touted the deployments as a way for troops to get hands-on experience in the mission, which cost $110 million in 2010, its first year.
But the Government Accountability Office issued a report in 2011 detailing Pentagon concerns about the lack of strategy for troops plugged into an ongoing, permanent mission executed by Homeland Security.
The spectrum of how troops could operate depending on their orders left Homeland Security struggling to figure out how to best utilize them, the report found.
There were other government worries.
"Department of State and DOD officials expressed concerns about the perception of a militarized U.S. border with Mexico, especially when State and Department of Justice officials are helping support civilian law enforcement institutions in Mexico to address crime and border issues," the report found, referring to the Department of Defense by its initials.
In late 2011, Obama scaled back the mission to focus on aerial surveillance.
Other notable deployments occurred during this period.
In 2014, then-Gov. Rick Perry, a Republican, dispatched about 1,000 Texas National Guard troops to the southern border after an influx of unaccompanied minors from Central America seeking asylum in the United States. Air Force bases were used as temporary shelters for the children.
A Section on 04/05/2018