In a powerful display of military might, Japanese and South Korean warships separately trained with three U.S. aircraft carriers on Sunday as the allies presented a united front against nuclear-armed North Korea.

Japan sent its massive Ise helicopter destroyer — one of the largest warships in its fleet — as well as the Inazuma and Makinami destroyers, for the joint military exercises in the waters near the Korean Peninsula. They joined the Yokosuka, Kanagawa Prefecture-based USS Ronald Reagan and the USS Nimitz and USS Theodore Roosevelt aircraft carrier strike groups.

It was the first time the Maritime Self-Defense Force had drilled with so many carriers.

The MSDF said it was “using every opportunity” to strengthen the two navies’ ties, and joining the three-carrier flotilla for drills was “natural” as part of efforts “to “stabilize” the regional security situation.

Following the bilateral exercise, the U.S. vessels also linked up with seven South Korean warships, “the first time that three U.S. aircraft carriers have joined together at close range for a joint exercise with South Korea,” the Yonhap news agency reported.

“The combined drills are to present our resolve and will to deter North Korea’s provocations and retaliate if provoked,” Yonhap quoted a South Korean official as saying.

The rare three-carrier exercises kicked off Saturday and will run through Tuesday in a show of force that coincides with the final leg of U.S. President Donald Trump’s Asia tour.

It is the first time three carrier strike groups have operated together in the area since 2007, and comes amid growing tensions on the Korean Peninsula over Pyongyang’s nuclear arms and ballistic missile programs.

Trump has used his Asia tour to wrangle support for further isolating nuclear-armed North Korea, which conducted its largest-ever nuclear test in September and has test-fired dozens of missiles this year — including some thought capable of striking the mainland United States.

Amid the U.S. military shows of strength, North Korea vowed Saturday to defend its “sovereignty and rights to existence and development by keeping a real balance of force with the U.S.”

That sentiment echoed earlier charges by Pyongyang that it will continue to seek a “final goal” of military “equilibrium” with the United States.