Defense Secretary James Mattis authorized the National Guard troops deployed to the southwest border to stay there for another year, the Pentagon confirmed Friday.

Mattis granted a 12-month extension of the current deployment order, which authorizes up to 4,000 guardsmen to support U.S. Customs and Border Protection (CBP) agents until Sept. 30, the end of the current fiscal year.

The extension permits the same deployment through Sept. 30, 2019, Pentagon spokesman Lt. Col. Jamie Davis told The Daily Caller News Foundation.

“It’s the same mission, the same set up,” Davis said.

The border deployment, dubbed Operation Guardian Support, kicked off April 13 in response to President Donald Trump’s call to use the military to guard against rising illegal immigration. A joint operation with the Department of Homeland Security (DHS), the mission aims to provide surveillance and logistical support to border agents, freeing them up to interdict drug and human smuggling.

There are currently about 2,200 National Guard soldiers deployed to the four states along the southwest border, Davis said. There are 1,145 soldiers in Texas, 115 in New Mexico, 580 in Arizona and 360 in California.

The border states are contributing the majority of the guardsmen deployed with Guardian Support, while several other states are providing aviation assets. Other states participating in the mission as of June were Missouri, Indiana, Maine, Wisconsin, Arkansas, Tennessee, Kentucky, Mississippi, Oklahoma, Louisiana, South Carolina, Georgia, Alabama and Florida, reports Stars and Stripes. (RELATED: Eight State Governors Pull National Guard Assets From Border)

It remains unclear how the Pentagon will fund a border deployment in the next fiscal year. For the current deployment, Congress granted reprogramming requests that allow the Pentagon to shift hundreds of millions of dollars from the Army’s general account to its personnel account for the National Guard.

The same funding mechanism is expected to be used in FY2019, Davis said.

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