Plans to launch live artillery shells over a key Southern California highway during a military event attended by Vice President JD Vance faced strong opposition from Governor Gavin Newsom. Concerns about safety compelled him to temporarily shut down a segment of the heavily trafficked interstate on Saturday.

“The President’s actions prioritize ego over safety, showing a blatant disregard for public welfare,” stated the Democratic governor. “Launching live rounds over a bustling highway is not only inappropriate but also perilous,” he added.

However, officials from the U.S. Marine Corps defended the exercise at Camp Pendleton, asserting that artillery fire is a standard operation there. They argued that halting traffic on Interstate 5, the primary coastal route between San Diego and Los Angeles, was unwarranted.

The decision to close the highway drew criticism from Republicans.

U.S. Representative Darrell Issa, whose district lies east of the base, condemned the closure as “a vindictive publicity maneuver” by Newsom.

Vance, a Republican, and Defense Secretary Pete Hegseth visited the base in north San Diego County to celebrate the Marine Corps’ 250th anniversary, and watch troops put on a show of amphibious vehicles and Marines demonstrating a beach assault. Vance, a Marine Corps veteran, and his wife, Usha, watched as aircraft shot across the sky and columns of smoke rose from munitions strikes.

The state had considered closing the freeway earlier in the week, but the U.S. Marines said Thursday that the event would occur on approved training ranges and comport with established safety protocols.

State transportation officials ultimately made the decision to close the freeway after practice firings Friday evening and a request from event organizers for signage along the road stating “Overhead fire in progress.”

The California Highway Patrol closed a 17-mile (27 kilometers) stretch of the highway for periods before and during the Saturday exercise. Severe traffic delays were reported Saturday morning and early afternoon. No mishaps were reported related to the artillery fire.

“This is all because of the White House-directed military event, that for the safety of the public, we need to shut down the freeway since they’re sending live ordinances over the freeway,” California Department of Transportation spokesperson Matt Rocco said.

U.S. Marines Capt. Gregory Dreibelbis said in a statement that there is artillery fire at the base nearly every week and that the exercises didn’t endanger motorists.

“Weeks of deliberate planning and rehearsals ensured success at every phase of execution,” he said.

In a statement to The New York Times, a spokesperson for Vance, William Martin, said Newsom misled the public about the safety risk.

“If Gavin Newsom wants to oppose the training exercises that ensure our Armed Forces are the deadliest and most lethal fighting force in the world, then he can go right ahead,” Martin said.

Rocco said the I-5 closure could cost up to another two hours of trip time for those commuting between San Diego and Los Angeles. The freeway carries 80,000 travelers and $94 million in freight through the corridor daily, according to the governor’s office. Passenger rail services running parallel to the I-5 have also been canceled for the afternoon.