U.S. President Barack Obama’s visit to Hiroshima later this month will have many implications for the world and South Korea as well.

Most of all, the first visit by the incumbent U.S. leader to the place where it dropped an atomic bomb 71 years ago should reawaken the world to the need to get rid of the most menacing weapon of destruction ever made by mankind.

In fact, Obama has tried to build nuclear disarmament and nonproliferation as a key legacy of his presidency. He kicked off his denuclearization initiative in an address in Prague shortly after he took office in 2009, and masterminded the Nuclear Security Summit.

So, he must have thought that visiting Hiroshima could lend a symbolic complement to his signature initiative. Obama’s spokesman aptly stated that his visit will “highlight his continued commitment to pursuing the peace and security of a world without nuclear weapons.”

Now that Obama has decided to go, what he has to do -- and what he should not do -- is obvious. First, he should at least express regret over the human mistake of developing and using the most vicious and savage weapon in human history.

Some still justify the use of atomic bombs for ending Japanese resistance in the final phase of the Pacific War. White House aides also said that Obama “will not revisit” the decision to use the atomic bomb at the end of World War II.

But some regrets -- addressed not to what was imperialist Japan but to the victims who did not even know what they were being killed by -- would help build the consensus that there should never be a second Hiroshima and Nagasaki.

That would be the least that Obama -- as a descendant of people whose decision killed about 210,000 innocent people in the two cities, including 40,000 Koreans -- can do to make up for the human mistake of producing and using a weapon with such colossal power for destruction and console the victims and their bereaved families.

But any remorseful attitude expressed by Obama should not allow Japan to magnify its image as a “victim” rather than an aggressor of the Pacific campaign, which killed more than 20 million people, including hundreds of thousands of Koreans.

We call the U.S. leader’s attention to this because Japan has yet to show full repentance over its wartime past and its endeavors to become a “normal state,” including expansion of its military’s role overseas, are still a cause of concern. Obama’s visit should serve as a reminder that Japan itself is responsible for waging the war and inviting the atomic attacks and more importantly, that it should not take an expansionist path again.

North Korea is another issue Obama should not forget to mention in Hiroshima. Obama will be in the city, which is within a few hours‘ flight from Pyongyang, at a time when North Korea is under the toughest-yet sanctions over its latest nuclear and missile provocations.

In the Prague address on his denuclearization initiative, Obama said that his initiative would include preventing the production of more nuclear weapons, negotiating a new international treaty and strengthening the Nuclear Nonproliferation Treaty. The current standoff between the world and the rogue regime in Pyongyang shows that Obama’s initiative has hit a big stumbling block on the peninsula. He must at least offer a clue as to how to overcome this.