South Korean marines on patrol, March 2013
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The Korean crisis - in 90 seconds

3 April 2013 Last updated at 19:08 BST

North and South Korea have technically been at war since the 1950s, but tensions on the peninsula regularly flare up.

This time the temperature has been rising since the North tested a missile in late 2012.

But is this round of North Korean provocation really any different from the last?

Adam Blenford reports.

Also produced by Katy Hastings