Bridget Kendall
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North Korea: How serious is military threat?

4 April 2013 Last updated at 15:33 BST

Pyongyang earlier renewed threats of a nuclear strike against the US, though its missiles are not believed to be capable of carrying nuclear warheads.

The US is responding by moving missile defence shields to Guam.

The BBC's Bridget Kendall explains how serious the increasing military threat from North Korea is.