SAN DIEGO — While a naval officer sang the first notes of “The Star-Spangled Banner” and dozens of military members unfurled an oversized flag on the football field, Colin Kaepernick and Eric Reid dropped to one knee on the San Francisco 49ers’ sideline.

With his silent gestures of protest, Kaepernick intends to keep drawing attention to a litany of American problems — and he’s no longer alone.

Kaepernick and Reid kneeled during the national anthem Thursday before the 49ers’ 31-21 preseason victory over San Diego, ignoring scattered boos and angry shouts in Qualcomm Stadium at the Chargers’ Salute to the Military preseason game.

Up north in Oakland, Seattle Seahawks cornerback Jeremy Lane showed his support for Kaepernick by sitting on the bench during the anthem.

“I’m not anti-American. I love America,” said Kaepernick, who stayed on the field long after the game to sign autographs for enthusiastic fans. “I love people. That’s why I’m doing this. I want to help make America better, and I think having these conversations helps everybody have a better understanding of where everybody is coming from.”