Returning to the topic of whether he would order the military and law enforcement to shoot people who throw rocks, President Donald Trump on Friday said migrants who throw stones at the border will be arrested, not shot.

“They won’t have to fire. What I don’t want is I don’t want these people throwing rocks,” Trump said on the White House’s South Lawn. “They do that with us, they’re going to be arrested.”

When asked if he could guarantee that American troops would not open fire in a chaotic situation, the commander in chief replied: “I hope not.”

His latest comments come as he uses the immigration issue and migrant caravans to rev up his conservative base for the 2018 midterms.

A day earlier, Trump said any projectile stones would be treated by military forces the same as “firearms” as he aggressively tries to make two Central American migrants groups headed to the U.S.-Mexico border a defining issue of the final days of midterm election campaigning.

But on Friday, as he left the White House campaign rallies in two battleground states (Senate battlegrounds West Virginia and Indiana), the president clarified his stance to say rock-tossers will instead be arrested.

Existing U.S. laws prohibit military troops from making arrests on domestic soil. Presumably, Border Patrol and other federal, state and local law enforcement officers would make any such arrests.

A day after he said his administration intends to erect tent cities to detain — rather than release into the United States — undocumented migrants who enter the country illegally, Trump signaled he wants any rock throwers to be arrested and detained for a “long period of time.”