Adm. Harry Harris, who stepped down today as head of U.S. Pacific Command, noted that since the end of the Cold War in 1991, much of the change in the Indo-Pacific region had been for the good.

“But make no mistake, our 27-year holiday from history is over,” Harris said in remarks at the Pearl Harbor change of command. “Great power competition is back.”

Adm. Phil Davidson, the former head of U.S. Fleet Forces Command on the East Coast, today took over the Pacific region that covers about half the globe — and some of the nation’s most pressing defense challenges.

More than 750 people attended the command change at Kilo Pier — including Defense Secretary James Mattis; Gen. Joe Dunford, the chairman of the Joint Chiefs of Staff; and Chief of Naval Operations Adm. John Richardson.

Harris said President Donald Trump has made clear that geo-political competition between “free and repressive visions of the world order” is taking place in the region.

Reflecting ongoing change, Mattis announced that U.S. Pacific Command was changing its name to U.S. Indo-Pacific Command to underscore the importance of the Indian Ocean.

The command change came as U.S. officials scramble to salvage a June 12 Trump summit with North Korea. China’s military buildup in the South China Sea continues to raise tensions — leading the Pentagon last week to rescind China’s invite to participate in upcoming Rim of the Pacific war games off Hawaii.

“A resurgent and revanchist Russia, whose longest coastline is in the Pacific, remains an existential threat to the United States,” Harris said.

Harris has repeatedly taken a hardline against China’s expansionism in the South China Sea, which the United States worries will up-end a free flow of commerce and limit the U.S. military’s dominant role in the region since the end of World War II.

Harris graduated in 1978 from the U.S. Naval Academy. He became head of Pacific Command on May 27, 2015. He is retiring to become the next ambassador to South Korea.

For the Indo-Pacific Command “and for the allies, partners and friends assembled here today, Pacific Command must continue our good work to defend them and to deter our adversaries from attacking the United States,” Davidson said.