South Korea, the US and Japan staged their largest-ever joint naval exercise in international waters south of Jeju Island for three days through Wednesday, following North Korea’s launch of a hypersonic missile.

Nine warships including the nuclear-powered aircraft carrier USS Carl Vinson with F-35C stealth fighters and F-18 Super Hornets on board, South Korean Aegis combat system-equipped destroyers and Japanese Kongo-class destroyers took part in the drill.

The maritime exercise began a day after North Korea test-fired a solid-fuel intermediate-range ballistic missile with hypersonic capabilities into the East Sea.

The flaunting of high-tech military power is likely to continue between North Korea and the three allies as the former escalates saber-rattling, with its leader vowing to delete from its constitution the concept that South Koreans and North Koreans are one people.

Kim Jong-un said the North should revise its constitution to define South Korea as its "invariable principal enemy" and to reflect its commitment to "completely occupying, subjugating and reclaiming" South Korean territory in the event of war, Pyongyang’s state media reported Tuesday.

Stressing that reunification with the South will never be peacefully realized, Kim said his country should "physically and completely" cut off its segment of cross-border railway tracks to "an irreparable extent" and tear down an "eye sore" monument in Pyongyang built to mark his grandfather Kim Il-sung's idea of reunification based on a federation.

The North also said its Supreme People’s Assembly has decided to disband agencies committed to promoting inter-Korean dialogue and cooperation.

President Yoon Suk Yeol struck back at Kim, vowing to punish North Korea "multiple times harder" if it provokes South Korea.

Yoon also said the Kim regime has admitted the fact that it is an anti-nationalistic and anti-historical group by identifying inter-Korean relations as that of two antagonistic countries.

North Korea is also providing Russia with missile launchers and ballistic missiles as well as artillery shells for use in its war with Ukraine, although the two have officially denied it.

Panic and anxiety is exactly what Pyongyang has tried to achieve through its verbal attacks and demonstrations of new weapons since the Korean War.

Rep. Thae Yong-ho, a former North Korean diplomat who defected to the South in 2016, downplayed a US expert’s view that Kim has decided to go to war like his grandfather in 1950, saying the situation is different now, with the ROK-US alliance, US Forces Korea, and the US nuclear umbrella.

As Pyongyang is selling tons of weapons to Russia, Kim is uneasy that the South and the US might suddenly attack it, Thae said in media interviews, adding that Kim is stepping up his war of words to conceal this insecurity and to affect the general election in the South and the US presidential election.

Other North Korea watchers also say the chances of an all-out war are low, while there is a higher possibility of accidental clashes or exchanges of fire.

South Korea should continue to demonstrate fortitude like it is doing now, by fully mobilizing its intelligence capabilities, and rigorously analyze all possibilities heading toward the US presidential election in November.

Victor Cha, Korea Chair at the US think tank Center for Strategic and International Studies, said in a virtual forum on Tuesday that it is “not implausible” that Donald Trump, if reelected as US president, could “basically accept North Korea as a nuclear state as long as they didn’t fire ICBMs in the direction of the US,” and then lift sanctions.

Since money is Trump’s primary compass for foreign policy, there would be “less US-Japan-ROK military exercising which he doesn’t like because it’s too expensive,” Cha said.