President Trump has signed a proclamation to send the National Guard to the U.S.-Mexico border, the White House said. Secretary of Homeland Security Kirstjen Nielsen had announced the expected move earlier Wednesday.

Gritty details: The order does not disclose details such as cost or number of troops to be deployed. But it said that the defense and homeland security secretaries are required to submit a report within 30 days on "an action plan," including recommendations for potential executive authorities on border security.

Nielsen had urged Congress to “close loopholes that exacerbate” problems at the border and should allocate additional funding for detention centers and a wall.

Why now? Nielsen said the proposal has been on the table for a while and that it will be implemented in conjunction with border-state governors.

For context: Sending the National Guard at the border is not new. Former presidents George W. Bush and Barack Obama sent troops as well, costing taxpayers more than $1.3 billion, per CNN. However, the troops only assisted with surveillance efforts, but didn’t directly engage in removing people from the border.