PHOENIX (AP) — The 5,200 active-duty troops being sent by President Donald Trump to the U.S.-Mexico border will be limited in what they can do under a federal law that restricts the military from engaging in law enforcement on American soil.
That means the troops will not be allowed to detain immigrants, seize drugs from smugglers or have any direct involvement in stopping a migrant caravan that is still about 1,000 miles from the nearest border crossing.
Instead, their role will largely mirror that of the existing National Guard troops — about 2,000 in all — deployed to the border over the past six months, including providing helicopter support for border missions, installing concrete barriers and repairing and maintaining vehicles. The new troops will include military police, combat engineers and helicopter companies equipped with advanced technology to help detect people at night.
The extraordinary military operation comes a week before the Nov. 6 midterm elections as Trump has sought to transform fears about the caravan and immigration into electoral gains. On Tuesday, he stepped up his dire warnings, calling the band of migrants fleeing poverty and violence in Central America an "invasion."
"Our Military is waiting for you!" he tweeted.
Traveling mostly on foot, the caravan of some 4,000 migrants and a much smaller group of hundreds more are still weeks, if not months, before reaching the U.S. border. Thousands have already dropped out, applying for refugee status in Mexico or taking the Mexican government up on free bus rides back home, and the group is likely to dwindle even more during the arduous journey ahead.
Another smaller caravan earlier this year numbered only a couple hundred by the time it arrived at the Tijuana-San Diego crossing.
And despite the heightened rhetoric, the number of immigrants apprehended at the border is dramatically lower than past years. Border Patrol agents this year made only a quarter of the arrests they made in 2000 at the height of illegal immigration, when the agency had half of the staffing it does today. The demographics have also drastically changed, from mostly Mexican men traveling alone, to Central American families with children.
Migrants arriving at the border will now see a sizable U.S. military presence — more than double the 2,000 who are in Syria fighting the Islamic State group — even though their mission will be largely a support role.
That's because the military is bound by the Posse Comitatus Act, a 19th- century federal law that restricts participation in law enforcement activities. Unless Congress specifically authorizes it, military personnel can't have direct contact with civilians, including immigrants, said Scott R. Anderson of The Brookings Institution.
Instead, the large troop deployment will be limited to performing similar support functions as the National Guardsmen and women Trump has already sent to the border.
These include 1,500 flight hours logged by about 600 National Guard troops in Arizona since they were deployed this spring. Members of the guard have also repaired more than 1,000 Border Patrol vehicles and completed 1,000 hours of supply and inventory, according to Customs and Border Protection.
In one case, a group of Border Patrol agents tracking drug smugglers in the remote Arizona desert in August called on a National Guard helicopter to keep an eye on the suspects and guide agents on the ground until they had them in custody. That operation resulted in several arrests and the seizure of 465 pounds of marijuana.
In addition to the 5,200 troops being deployed this week, the Pentagon has put another 2,000 to 3,000 active-duty troops on standby in case they also are needed at the border, a U.S. official said Tuesday, speaking on condition of anonymity to discuss a detail that has not been publicly announced.
The troops were being sent initially to staging bases in California, Texas and Arizona while Customs and Border Protection works out precisely where it wants the troops positioned.
It remains unclear why the administration was choosing to send active-duty troops given that they will be limited to performing the support functions the Guard already is doing.
"Sending active military forces to our southern border is not only a huge waste of taxpayer money but an unnecessary course of action that will further terrorize and militarize our border communities," said Shaw Drake, policy counsel for the American Civil Liberties Union's border rights center at El Paso, Texas.
The California National Guard has pledged up to 400 troops to the president's border mission through March 31. Jerry Brown, the only Democratic governor in the four states bordering Mexico and a frequent Trump critic, conditioned his support on the troops having nothing to do with immigration enforcement or building border barriers.
Brown said the California troops would help fight transnational criminal gangs and drug and firearms smugglers.
In New Mexico, 118 Guard troops have been helping with vehicle maintenance and repair, cargo inspection operations, surveillance and communications.
Texas Gov. Greg Abbott pledged 400 troops to the border in April. Maj. Gen. John Nichols, the head of the Texas National Guard, told Congress in July that his troops served in a "variety of support roles," including driving vehicles, security monitoring, and administration.