U.S. Pacific Command, the oldest and largest of the military’s major commands, officially received a name change Wednesday, reflecting evolving priorities, including a “great power” competition with China.

Henceforth, the Oahu-based command, created in 1947, will be known as U.S. Indo-Pacific Command, emphasizing the growing importance of the Indian Ocean and India itself to U.S. strategy in the region.

Defense Secretary James Mattis announced the name change as Adm. Phil Davidson, the former head of U.S. Fleet Forces Command on the East Coast, took over the Pacific region that covers about half the globe — and some of the nation’s most pressing defense challenges. Davidson replaces Adm. Harry Harris.

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

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

In his remarks, Harris noted that since the end of the Cold War in 1991, much of the change in the Indo-Pacific region has been for the good.

“But make no mistake, our 27-year holiday from history is over,” Harris said. “Great power competition is back.”

The command change came as U.S. officials scramble to salvage a June 12 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 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,” meanwhile, Harris said.

Harris has repeatedly taken a hardline against China’s expansionism in the South China Sea, which the United States worries will upend 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 after 40 years of military service to become the next ambassador to South Korea.

Harris “steered a steady ship amid often shifting ocean currents,” Mattis said. “You anticipated our nation’s needs with remarkable foresight.”

His replacement, Davidson, has over 36 years in uniform and brings a “wealth of operational and strategic experience” to the new role, Mattis said.

Mattis and Dunford, the joint chiefs chairman, also met with Japanese Defense Minister Itsunori Onodera and members of his cabinet at Joint Base Pearl Harbor- Hickam. Mattis is heading on to Singapore for what’s known as the “Shangri-La Dialogue” to discuss America’s Indo-Pacific interests.

Before arriving in Hawaii, Mattis had said a “very steady drumbeat of freedom of navigation operations” is planned in the South China Sea to challenge China’s military buildup on contested islands.

China “is no longer a rising power but an arrived great power and peer competitor,” and the United States should respond by adding military forces in the Pacific, Davidson told the Senate Armed Services Committee in April.

Davidson testified that he is increasingly concerned about China.

“China has undergone a rapid military modernization over the last three decades and is approaching parity in a number of critical areas; there is no guarantee that the United States would win a future conflict with China,” he said.

Indo-Pacific Command is “heavily dependent” on high-end warfare capabilities including stealth aircraft, munitions capable of breaching China’s defenses, and submarine dominance, he said.

Davidson said the United States should continue to invest in next-generation capabilities such as long-range hypersonic missiles “while simultaneously recognizing that China is already weaponizing space and cyber.”

He added he would closely examine the number and types of ships and infrastructure to support them in the Pacific.

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 at the command change.