Defense experts say Seoul needs to overhaul its entire national security policy on the assumption that North Korea is or will soon be armed with nuclear missiles.
The South Korean military's current operational plans are based on the assumption that the North has only basic nuclear bombs that have to be carried by bomber planes.
But now pundits say North Korea is at least close to miniaturizing nuclear warheads so they could be fitted on missile.
One former senior military intelligence officer said the North has a roadmap for developing nuclear warheads for missiles and will stick to it.
India and Pakistan succeeded in miniaturizing their nuclear weapons just two or three years after they carried out a nuclear test. In North Korea, more than six years have already passed since the first nuclear test in October 2006.
That suggests Seoul needs to hurry to work out a response, especially against the North's nuclear missiles, while at the same time continuing dialogue and negotiations with Pyongyang.
Prof. Yun Duk-min of the Korea National Diplomatic Academy warned South Korea could face a crisis that would expose it to the North's so-called asymmetric warfare capabilities, where it has the edge over the South, unless Seoul comes up within two or three years with a weapons system that can counter the North's nuclear armament.
The best policy would be to stop any nuclear-tipped missiles even taking off, since a single device would wreak unimaginable devastation here. But experts say there is no way South Korea can launch a preemptive strike on North Korea's Yongbyon nuclear complex in peacetime the way Israel bombed the Osirak nuclear reactor in Iraq in 1981.
A secret simulation by the military about 10 years ago found that nuclear fallout from bombing the Yongbyon reactor would also reach South Korea.
Still, some pundits are calling for plans for last-minute preemptive precision strikes if the North in an emergency seems poised to launch a nuclear missile.
Others tend more toward an effective missile defense shield.