President Donald J. Trump, Vice President Mike Pence, Defense Secretary Dr. Mark T. Esper and other officials watched as Marine Corps Gen. Joe Dunford swore in his successor.
Milley is the 20th chairman since the position was established in 1947.
"You can rest assured that I will always provide informed, candid, impartial military advice to you, the Secretary of Defense, the National Security Council and to the Congress," Milley said.
Milley takes over as the military's highest-ranking officer, guiding a force of the 3 million service members. He noted that U.S. service members serve "on freedom’s frontier" — many in harm's way — in more than 160 countries.
Milley thanked Dunford and Dunford's wife, Ellyn, for the examples they set. "I know that I have big shoes to fill," Milley said.
"I have known Joe Dunford throughout my career, served with him in combat, and I consider him a close personal friend — a friendship forged with the unbreakable bonds of combat that only shared sacrifice can produce. It is truly an honor to follow Gen. Dunford and become the next in a long line of distinguished chairmen."
Milley said he will work with his fellow joint chiefs, combatant commanders and senior leaders across the government to address national security issues.
"I see in the audience today also many chiefs of defense from around the world," he said. "Your presence here today demonstrates the importance of our shared security interest and common values. As chairman, I look forward to working with all of you to ensure our collective security."
Milley said the the U.S. military faces complex challenges in the international environment, but said our service members are up to those challenges.
"We are the best-equipped, best-trained, best-led military in human history, and our adversaries should know never to underestimate our skill, our capability and our combat power," he said. "We will remain the world's premier fighting force — respected by our friends and feared by our adversaries. We will do this by emphasizing readiness and the modernization of the joint force, all while providing unwavering support, and care, and leadership to our troops and their families."
Esper thanked Dunford for more than 40 years of service. Former President Barack Obama appointed Dunford as chairman in 2015, and President Trump renominated Dunford for the job in 2017.
Esper said he observed Milley's talent and dedication while the general was Army chief of staff and Esper the service secretary.
"During his time as chief of staff, he was instrumental in helping to rebuild the Army's readiness, which suffered from years of insufficient defense budgets," Esper said. "At the same time, he advanced the Army's ability to prepare for future warfare by standing up Army Futures Command, the largest organizational change within the service in 45 years. The president could not have selected a more competent advisor or a more capable soldier to help prepare our military for the challenges of the future."
President Trump congratulated Dunford on a job well done and thanked Milley for accepting the position. "In his new role as chairman of the Joint Chiefs of Staff, General Milley will serve as my top military advisor," Trump said. "I have absolute confidence that he will fulfill his duty with the same brilliance and fortitude he has shown throughout his long and very distinguished career.
"From the great General Omar Bradley to the famed Joe Dunford," he continued, "our nation has been blessed by the advice, counsel and wisdom of 19 chairmen of the Joint Chiefs of Staff. Today, we pass the baton to the 20th."