The leaders of 53 nations and international bodies met in Seoul for two to reconfirm their shared responsibilities to keep nuclear materials from dangerous hands, but the absence of North Korea and Iran helped the participants of the 2012 Nuclear Security Summit realize where the biggest threats are.

One positive outcome for President Lee Myung-bak, host of the second nuclear summit after the first in Washington in 2010, was that he had a great opportunity to convince world leaders of the nature of the troubles posed by the North, including the imminent test-firing of a long-range missile. Pyongyang rather helped Lee by threatening that any hostile move against its “rocket launch” would meet “unimaginable consequences.”

The Nuclear Security Summit taking place across the North-South border also offered a chance for Kim Jong-un to portray himself to the international community as the new leader of a regime that has constantly harassed the regional and global security with its nuclear ambitions and roguish acts. Pyongyang’s announcement of the mid-April rocket launch schedule was the outright scrapping of an agreement it made with the United States in February and a blatant challenge to the international community prior to the nuclear security forum.

Thus, U.S. President Obama served a strong message to the North by visiting a guard post on the border to watch the source of the threats himself immediately after landing here on Sunday. He indicated that Washington would not carry out its commitment of food aid under the Feb. 29 agreement in Beijing unless the North canceled the launch.

China’s President Hu Jintao, in a clear departure from Beijing’s characteristic ambivalence, joined President Lee in demanding Pyongyang give up the rocket launch, which they determined as detrimental to peace on the Korean Peninsula and the six-party process to denuclearize the North. He even informed Lee that Beijing had pressed Pyongyang leadership to concentrate on economic development instead of its alleged satellite program.

In separate talks with Russian President Dmitri Medvedev and a dozen other leaders, President Lee shared concerns about Pyongyang’s nuclear and missile programs. Obama and Hu are also reported to have discussed the North Korean situation in their conversations outside the nuclear summit proceedings. The serious note in these dialogues regarding North Korea was reflected in the Seoul Communique.

The probability that Kim Jong-un and his guardians in Pyongyang would listen to the collective calls from Seoul and change their minds about the rocket program appears to be nil, as it is aimed to consolidate the new leader’s grip on power and particularly to ensure the allegiance of the military. The young successor would never want to expose his weakness by succumbing to international pressure.

Still, we do not believe that the discussions by the leaders and their aides at the Nuclear Security Summit and in the course of its preparations were entirely useless as far as the North is concerned. Especially, it would be hard for Pyongyang to ignore its closest ally Beijing’s resolute statement against its launch plan. The 240,000-ton nutritional aid Washington had promised in exchange for a halt to its nuclear and missile programs must be too enticing to lose entirely.

Surveillance satellites have detected the arrival of the rocket body in the launch site of Dongchang-ri on the west coast of North Korea. If Pyongyang leaders have the modicum of reason needed to weigh what they would gain and lose by firing “Bright Star 3,” the North could come up with a revision of the original rocket launch schedule. They may seek to amend relations ex post facto, but it would be too late.

The Seoul Communique on the reduction of highly-enriched uranium and separated plutonium, safe management of weapons-usable nuclear materials, protection of nuclear-related facilities and prevention of illicit trafficking of nuclear materials show progress in the last few years in nuclear security efforts. Yet, nations should recognize the slowness of processes to harness nuclear power. The six-party talks that remain stalled nine years after being launched in Beijing are the most frustrating example.

The outcome of the Seoul summit will be measured how the leaders will henceforth translate their respective responsibilities into practical actions back in their capitals.