IMPERIAL BEACH, Calif. — Cmdr. Alyssa Armstrong relieved Cmdr. Brandon Castle as commanding officer, Maritime Expeditionary Security Squadron (MSRON) 3, during a change-of-command ceremony at Naval Outlying Landing Field, Imperial Beach, Calif., March 21, 2025.

Castle, from Fremont, Calif., led a team of more than 300 Sailors during his 18-month tenure at MSRON-3 from Nov. 2023 to Mar. 2025. His next assignment will be serving as the Commanding Officer of Maritime Expeditionary Security Training and Evaluation Unit (TEU) One, based in Imperial Beach, Calif.

“It has been an honor and privilege to wear the MSRON-3 patch and work for this team,” said Castle. “We completed every mission given to us, supported other teams when we were asked and supported each other when it was needed. Thank you for everything we accomplished while I was fortunate enough to be on the team.”

Armstrong, from Gaithersburg, Md. was selected as commanding officer after completing a successful tour as MSRON-3’s executive officer.

“I am incredibly excited to lead the seasoned team of leaders at MSRON-3,” said Armstrong. “We are a more lethal, expeditionary force because of Cmdr. Castle’s legacy, and I look forward to building further upon it as our teams deploy worldwide in support of harbor and embarked maritime security.”

MSRON-3’s mission is to provide high-value asset escorts, harbor area defense, embarked, and aviation security teams, and when directed, conduct combat operations to dominate the littorals and reinforce blue water operations.