North Korea mentioned the development of an electromagnetic pulse (EMP) weapon for the first time on Sept. 3. In a statement about its leader Kim Jong Un’s inspection of a new hydrogen bomb, the reclusive nation insisted, “It’s a thermonuclear warhead that can be detonated at high altitudes for a super-powerful EMP attack on a wide area.”

Following Pyongyang’s declaration that it has acquired the ability to carry out an EMP attack, CNN TV warned the same day, “One blast could knock out power and communications over hundreds or even thousands of kilometers,” citing a report published by the U.S. Department of Energy in January.

An EMP bomb is a nuclear weapon designed to be detonated at a very high altitude of up to about 400 km in order to create extremely powerful EMPs. Such pulses wipe out the entire social infrastructure, such as electricity, communications, and transportation, without directly killing human beings or destroying buildings. A single EMP attack can cause severe damage and highly electrified advanced nations are particularly vulnerable.

A U.S. military source says that the U.S. “has taken thorough measures for key facilities that will be hubs in contingencies” to defend against EMP bombs. But Japan and South Korea have not taken enough measures against such bombs.

Japan’s Chief Cabinet Secretary Yoshihide Suga told reporters on Sept. 6 that the Japanese government is “gathering and analyzing information with great interest” to deal with the EMP threat. But Tokyo has no specific measures to protect infrastructure facilities from EMP attacks. “The government has no unified measures,” said a senior official of the Cabinet Secretariat.

An insider from Japan’s Defense Ministry insisted on Sept. 6 that intercepting [an EMP bomb] before detonation is an effective measure, and said, “It’s important to prevent a nuclear bomb from detonating to avoid an EMP attack.” The person also said that in order to guard against EMPs in case of a bomb’s detonation, “Ultimately we need to cover objects with heavy-duty iron and independently generate power inside.” But the person adds, “It’s financially impossible to take measures for all equipment.”

South Korean Defense Minister Song Young-moo said on Sept. 4, “We can protect major command centers like the Joint Chiefs of Staff. But we are still unable to protect battalions and divisions.” According to the Yonhap News Agency, only three of the 221 South Korean military facilities were protected (as of 2012.)

A South Korean military source says that if electronic devices are destroyed, “Fighter jets will be unable to identify their own locations and tanks won’t be able to move.” It will also make it difficult to distinguish between friends and foes, and missiles cannot be intercepted if radar is wiped out. The source adds, “Advanced technology is an asset of the U.S. and South Korean forces, but it is also a vulnerability.” (Abridged)