ARI SHAPIRO, HOST: President Biden has asked the military to look into making the COVID-19 vaccine mandatory. The Department of Defense admits vaccination rates are around 50%, no higher than the rest of the nation. And concerns are growing about the more contagious delta variant. Steve Walsh of member station KPBS in San Diego covers the military. Good to have you here. STEVE WALSH, BYLINE: Hi, Ari. SHAPIRO: Explain what the president is asking the military to do exactly. WALSH: So the president is directing Secretary of Defense Lloyd Austin to look at what steps need to be taken to mandate the vaccine. Now, many congressional Democrats have been urging Biden to just go ahead and mandate it for the military, which he could do as commander in chief. He's been reluctant to do that. Right now, the vaccine is under emergency use authorization. There is a law that says the military cannot require treatment that is not fully approved by the Food and Drug Administration. That law is designed essentially to not allow the military to become guinea pigs for new treatments. Obviously, this is a bit different situation, though, since the very same vaccine is being administered to the general public already.