A plan to fire live artillery shells over a major Southern California highway as part of a military showcase attended on Saturday by Vice President JD Vance has drawn strong objections from Governor Gavin Newsom, who said safety concerns forced him to close a 27-kilometre portion of the interstate.

''The President is putting his ego over responsibility with this disregard for public safety,'' the Democratic governor said in a statement. ''Firing live rounds over a busy highway isn't just wrong -- it's dangerous.'' Vance and US Marine officials at Camp Pendleton have said there was nothing unsafe about the artillery exercise and no need to disrupt traffic on Interstate 5, which is the main highway along the Pacific coast between San Diego and Los Angeles.

The Republican vice president and

See Full Page