Donald Trump is deploying troops to the border. But border crossings are lower than they have been.

The U.S. Department of Homeland Security on Wednesday said a recent surge of apprehensions at the southern border justifies President Donald Trump’s decision to deploy National Guard units to the southern border, and released statistics the same day showing a double-digit spike in activity in March.

But critics of the plan argue that despite the increase, overall crossings are at historic lows. They add that it’s too soon to tell if the latest surge is indicative of a larger trend that will be similar to the heightened level of apprehensions in the Rio Grande Valley during 2013 and 2014, when a record number of Central Americans entered Texas illegally through Mexico.

Border crossings typically exhibit seasonal variations and tend to increase in the spring.

The March 2018 statistic also represents a 37 percent increase in people who were either apprehended between the ports of entry or deemed inadmissible to enter by federal customs and Border Patrol agents from a month earlier, from about 50,300 to February’s 36,700. Those figures include 1,099 unaccompanied minors and 5,127 families in March, increases from February’s 610 and 3,941, respectively.

Trump and DHS officials said the increase signaled a “crisis” at the border and argued that last year’s initial drop in apprehensions and attempted crossings after the president took office — the so-called Trump effect — was no longer in play.

But U.S. Customs and Border Protection’s own statistics indicate that despite the uptick in March, the total number of people apprehended or turned away since October, when the federal government’s fiscal year began, was lower than during the same six-month time frame in the previous fiscal year. This year, there have been about 237,000 apprehensions, compared to 2017’s 271,000.

Trump is not the first president to send national guard troops to the border. President George W. Bush sent about 6,000 national guard troops there in 2006. And President Barack Obama sent 1,200 guard troops to the border in 2010.

Talking to reporters on Air Force One late Wednesday, Trump said he wants to send between 2,000 and 4,000 National Guard members to the US-Mexico border, according to the Associated Press.

But many details of Trump’s border plan remain unclear, including exactly how many units will be deployed and where they will be stationed. Administration officials said Wednesday that the discussions with Texas Gov. Greg Abbott and other border governors are ongoing but stressed the move would happen quickly. But opponents wasted no time in predicting the deployment would be a waste of money and calling it nothing more than a reaction to Congress failing to fully fund complete construction of a border wall in last month’s $1.3 trillion spending bill.

“There’s nothing surprising about Trump’s plan to falsely increase fear about our border with Mexico; it’s part of his political origin story,” said Tom Jawetz, the vice president of Immigration Policy at the progressive Center for American Progress. “It is also now clear that Congress will not give him the money to begin construction of his ‘big, beautiful wall.’”