In a TODAY exclusive, Secretary of Defense Mark Esper says he’s “very concerned” about Thursday’s shooting at a naval base in Corpus Christi, Texas, as well as an earlier deadly attack on a base in Pensacola, Florida, and says “stringent steps” are being taken to prevent similar incidents. He says “absolutely it’s possible” for the Defense Department to have a coronavirus vaccine widely available by the end of the year: “We will deliver on time.” He also talks about National Guard deployment and his plans to honor service members over Memorial Day weekend.