U.S. President Donald Trump holds a joint news conference with Lithuania's President Dalia Grybauskaite and other Baltic leaders at the White House in Washington, U.S., April 3, 2018. REUTERS/Carlos Barria

WASHINGTON (Reuters) - President Donald Trump will sign a proclamation on Wednesday ordering the deployment of the National Guard to help protect the border with Mexico, Homeland Security Secretary Kirstjen Nielsen said.

“The president has directed that the Department of Defense and the Department of Homeland Security work together with our governors to deploy the National Guard to our southwest border to assist the Border Patrol,” Nielsen said at a White House briefing.

“The president will be signing a proclamation to that effect today.”