As Japan marks the 64th anniversary of the U.S. atomic bombings of Hiroshima and Nagasaki, the world sees two forces working in opposite directions when it comes to the issue of nuclear weapons.

On one hand, the opportunity has arisen to strengthen moves toward the global elimination of nuclear weapons. In an April 5 speech in Prague, U.S. President Barack Obama touched on the steps although he hinted at inherent difficulties in taking this direction. On the other hand, the danger from nuclear proliferation is increasing, as exemplified by North Korea, which conducted its second nuclear-weapons test May 25.

In his speech, Mr. Obama made clear the U.S. commitment "to seek the peace and security of a world without nuclear weapons." He also said that "as a nuclear power, as the only nuclear power to have used a nuclear weapon, the United States has a moral responsibility to act" toward building a nuclear-free world.

Admitting that the goal will not be achieved quickly, Mr. Obama said "I'm not naive." He then emphasized that as long as nuclear weapons exist, the U.S. will retain an arsenal to deter any adversary and guarantee the defense of its allies. Despite these qualifying conditions, it is significant that the U.S. president has committed his administration to the dream of a world without nuclear weapons.

Mr. Obama said his administration will seek U.S. ratification of the Comprehensive Nuclear Test Ban Treaty (CTBT) and negotiations on a new treaty to end the production of fissile materials used for producing nuclear weapons (the Fissile Material Cut-off Treaty). The U.S. will also negotiate with Russia this year on a new Strategic Arms Reduction Treaty.

The U.S. ratification of the CTBT could have a positive effect. In fact, former United Nations chief weapons inspector Mr. Hans Blix recently said: "The reality is that if the U.S. were to ratify (CTBT), then China would. If China did, India would. If India did, Pakistan would. If Pakistan did, then Iran would. It would set in motion a positive domino effect."

As the only nation to have experienced atom bomb attacks and the horrors of nuclear devastation, Japan can provide impetus to the efforts that would eventually lead to creation of a nuclear-free world. It should not miss the chance to work together with the U.S. toward this goal.

On April 27, Foreign Minister Hirofumi Nakasone delivered a speech titled "Conditions Toward Zero — 11 Benchmarks for Global Nuclear Disarmament." In the speech, Mr. Nakasone announced a Japanese plan to host an international conference early next year to push global nuclear disarmament. Japan needs to prepare carefully for the conference, and it may need to coordinate the event with Washington as Mr. Obama has already disclosed a plan for the U.S. to host a Global Summit on Nuclear Security within the next year.

Mr. Nakasone also called on the nuclear weapons states to carry out "irreversible nuclear disarmament" — taking steps that include dismantling nuclear warheads, nuclear testing sites and facilities that produce fissile materials for nuclear weapons. The nuclear weapons states under the Nuclear Nonproliferation Treaty (NPT) — the U.S., Russia, Britain, China and France — should remember that the treaty requires them to carry out disarmament. Only when these nations show concrete moves toward this end will they acquire the moral leverage needed to persuade other nations to give up their nuclear weapons or nuclear weapons programs.

In May 2010, there will be a five-year review conference of the NPT to examine the status of nuclear disarmament, nonproliferation and the peaceful use of nuclear energy. The last review conference in May 2005 was a failure. The international community should strive to make the coming review conference successful. It also must work to prevent terrorist groups from acquiring nuclear weapons.

North Korea's second nuclear test on May 25, 2009 (its first one was Oct. 9, 2006) has raised tension in Northeast Asia. At this moment, Pyongyang has shown no signs of giving up its nuclear weapons programs. It also has refused to return to the six-party talks aimed at denuclearizing the Korean Peninsula.

This situation appears to have given rise to an opinion within Japan that favors softening Japan's three-point nonnuclear principle of neither "producing" nor "possessing" nuclear weapons and not allowing them to be "brought in." But such an about-face would only give a country like North Korea an excuse to further push its nuclear weapons programs.

Efforts to create a world free of nuclear weapons should not be left only to national governments. The city governments of Hiroshima and Nagasaki and civic organizations can make great contributions. If more and more people worldwide correctly understand the truly catastrophic effects of nuclear weapons, they surely will become a great force in pushing for nuclear disarmament.