North Korea appears to be protesting the joint U.S. and South Korean military maneuvers by jamming Global Positioning Devices in the south, which is a nuisance for cell phone and computers users -- but is a hint of the looming menace for the military.

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The North is believed to be nearing completion of an electromagnetic pulse bomb that, if exploded 25 miles above ground would cause irreversible damage to electrical and electronic devices such as mobile phones, computers, radio and radar, experts say.

"We assume they are at a considerably substantial level of development," Park Chang-kyu of the Agency for Defense Development said at a briefing to the parliament Monday.
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