Having successfully whipped up election furor over the migrant caravan approaching the southern border of the United States, President Trump has announced his plan to stop it: sending 5,200 active-duty troops to the border. But sending troops to the border to meet an overblown threat of men, women, and children who have walked thousands of miles is a costly mistake.

For one thing, troops are limited in what they can actually do at the border. They aren’t going to be enforcing U.S. immigration laws, but instead manning places of entry, erecting tents, providing medical support and carrying out other logistical operations. Without proper statutory authorization, they can’t even engage in normal law enforcement activity.

[Trump: Asylum seekers can expect 'tent cities' upon reaching the US]

With similar past operations, like Obama’s Operation Phalanx in 2010, that has meant that many of the additionally deployed forces were assigned to watch and report, in what was criticized as an inefficient use of manpower.

But operations, even where forces don’t do much, still carry a huge price tag for taxpayers. The Obama operation cost $145 million over 14 months for and additional 1,200 troops. That deployment was the successor of President George W. Bush’s 2007 deployment of 6,000 National Guardsmen during Operation Jump Start. Over two years, that deployment cost $1.2 billion.

Trump’s operation, expected to last until mid-December, is likely going to cost millions of taxpayer dollars too. While this operation seems set to be much shorter, the rapid deployment of an addition 5,200 troops is not cheap, and the Pentagon has yet to release a cost estimate.

Already, the first 800 troops of this deployment were sent to the border on Monday with Gen. Terrence J. O’Shaughnessy telling reporters that “By the end of this week, we will deploy over 5,200 soldiers to the southwest border. That is just the start of this operation. We’ll continue to adjust the numbers and inform you of those.”

For a little perspective on just how big this border deployment is, once those 5,200 troops join the 2,000 National Guard members already on the border, there will be a larger U.S. military presence deployed against a migrant caravan than what we have currently in Iraq and Syria combined.

For a migrant caravan that has shrunk to 3,500, that massive military presence, in addition to existing border enforcement, certainly seems like overkill. Even with more migrants following the first group, there will likely be more than one U.S. officer or troop for each migrant.

With all the makings of an expensive boondoggle, this latest hard stand on immigration is a waste of taxpayer dollars that Trump must reconsider.