National Guard troops at the U.S.-Mexico border could be armed for self-defense purposes when they are deployed there, the head of the U.S. Border Patrol told reporters.

Chief Ronald Vitiello told reporters the decision on whether to arm the trooper will be left to the governors of each border state, especially if those troops are on missions that might force them to defend themselves, NBC News reported.

President Donald Trump announced his plans to send National Guard troops to the border April 4 because of increased illegal immigration there, NBC News said. At the time, it was widely reported that the troops would be unarmed.

"That's a case-by-case delegation, and that's determined by what the assignment is and most of the assignments won't require it," Vitiello said during a news conference at the Department of Homeland Security, per NBC News. "And then whatever the threat situation is, they'll be entitled to protecting themselves."

NBC News said Arizona has sent 250 troops to the border, while New Mexico has added 50, and Texas 650. The Department of Defense said, per the network, that it wants a total of 2,000 along the border by Sept. 30.

California Gov. Jerry Brown continued to his back-and-forth with the Trump administration on what role that state’s troops will play. The Los Angeles Times reported last week that California will deploy 400 National Guard troops, but Brown added that they will not enforce federal immigration law.

"Your funding for new staffing will allow the Guard to do what it does best: support operations targeting transnational criminal gangs, human traffickers and illegal firearm and drug smugglers along the border, the coast and throughout the state," Brown wrote in a letter to Homeland Security Secretary Kirstjen Nielsen and Defense Secretary James Mattis, the Times noted.

"This will not be a mission to build a new wall," Brown wrote, according to the newspaper. "It will not be a mission to round up women and children or detain people escaping violence and seeking a better life. And the California National Guard will not be enforcing federal immigration laws."

NBC News said arming National Guardsmen along the U.S.-Mexico border remains sensitive to some because of a 1997 incident in Texas' Rio Grande Valley in which an 18-year-old American goat herder was shot and killed by U.S. Marines patrolling the area for drug smugglers.