Central American migrants are seen outside and inside a temporary shelter Monday in Tijuana, Mexico. (Guillermo Arias/AFP/Getty Images)

About 300 hundred U.S. service members on the southern border have been shifted within the last few days from assignments in Arizona and Texas to work in California, near where a caravan of migrants has arrived in Mexico, U.S. military officials said Monday.

The troops were reassigned in coordination with U.S. Customs and Border Protection, which asked for assistance from the Pentagon to prepare for the arrival of Central American migrants. President Trump has lauded the use of the military at the border, even as Defense Secretary Jim Mattis has stressed that the troops will have no law enforcement role.

About 5,600 active-duty troops are supporting CBP on the border as of Monday, according to a statement released by U.S. Northern Command to The Washington Post. That’s down from a height of about 5,900, suggesting that some service members already have been sent home.

About 2,400 troops are in Texas, 1,400 are in Arizona, and 1,800 are in California, NORTHCOM said. Last week, the numbers were reported at about 2,800 in Texas, 1,500 in Arizona and 1,500 in California.

The recognition of more U.S. troops working on the California border comes a day after a clash at the San Ysidro border crossing there prompted CBP officers to take the rare step of firing tear gas into Mexico.

Lt. Gen. Jeffrey Buchanan, an Army general overseeing the deployment, said last week that he expected some U.S. troops could eventually be sent home as they were no longer needed. However, Pentagon officials have been vague about when that will occur or where.