OAKLAND, Calif. (AP) — This city’s year-old $18 million police radio system failed repeatedly during President Barack Obama’s visit to Oakland on Monday and during protests surrounding it.

Many of the 100 police officers assigned to presidential security duty that day were unable at times to communicate through their radios with police dispatchers, and even with each other, during the president’s fundraiser at a downtown theater, according to the head of the city’s police union.