Secretary of Defense James Mattis had officially signed off on the orders to extend the deployment of active-duty troops on the U.S.-Mexico border till the end of January. The deployment, which was requested by the Department of Homeland Security to help deal with large migrant caravans, was originally slated to end on December 15.

“The Secretary of Defense has approved an extension of the ongoing Department of Defense (DoD) support to the Department of Homeland Security (DHS) response to migrant caravan arrivals. DoD support to DHS is authorized until Jan. 31, 2019,” the DoD said in a statement on Tuesday.

During a press gaggle with reporters on Monday, Mattis said he had not sign the orders because the Joint Chiefs of Staff and his policy staff were still ironing out the details, but was expecting to have it on his desk within the day:

Mattis says he has not officially signed the order to extend the deployment of troops on the U.S.-Mexico border past December. He expects it to be on his desk within 24 hours. pic.twitter.com/NIA9yq66ZO — Julio Rosas (@Julio_Rosas11) December 3, 2018

In a statement announcing their request for the deployment to be extended, DHS said they need the support the U.S. military has been providing due to “the ongoing threat at our Southern border.”

“This request refines support to ensure it remains aligned with the current threat, the nature of the mission, and CBP operational requirements,” the DoD added.

The extension comes shortly after migrants tried to rush into the U.S. and threw rocks at border agents, who responded by using tear gas.