The deployment would increase the number of U.S. forces at the southwestern border by more than 45%, with the additional 2,100 troops joining roughly 4,500 personnel currently stationed there. The plan was approved Tuesday night by Richard Spencer, who assumed the role of acting defense secretary Monday while Mark Esper, President Donald Trump’s latest nominee for the position, faced confirmation hearings this week.

In deploying additional troops to the border, the Trump administration continued to signal concerns about the volume of immigration, which the president has repeatedly described as a crisis. The deployment follows similar actions by Mexico, which has sent thousands of troops to its borders with both the United States and Guatemala to curb immigration in recent months, drawing praise from Trump.

“I want to thank Mexico because they really have gone above and beyond,” Trump said Tuesday. “The borders were run by the cartels, and Mexico is taking back its country. And I give the president a tremendous amount of credit for that because that’s been going on for a long time,” he said, referring to President Andrés Manuel López Obrador of Mexico.

According to the Pentagon’s announcement, the additional troops will assist in securing points of entry and provide support in migrant holding facilities, including one in Donna, Texas, which Vice President Mike Pence visited last week as part of a highly publicized inspection of conditions in detention centers. A report this month by the Department of Homeland Security’s inspector general revealed widespread overcrowding and unsanitary living conditions in holding facilities.

In October 2018, the Trump administration sent more than 5,000 troops to the border, drawing criticism from Democrats and some former military officials who called it an excessive show of force or political showmanship on the cusp of the midterm elections. In recent months, however, attention has turned to how to appropriately manage the influx of mostly Central American migrants coming through Mexico, with both Democrats and Republicans largely in agreement that the existing infrastructure for holding and processing migrants at the border is overwhelmed.

This week, the Trump administration announced a plan to address the surge of immigration with a new policy denying asylum to migrants who do not apply for protection in at least one country they pass en route to the United States. The rule was contested by advocacy groups that filed a lawsuit Tuesday in federal court.

The decision to add more military personnel comes as border arrests dropped by 28% in June, following a trend in which border crossings decline during the hot summer months. It also coincides with the administration’s launch of raids to swiftly enforce deportation orders against some 2,000 recently arrived migrants who are not eligible to remain in the country.

This article originally appeared in The New York Times.