Why North Korea's fleet of outdated submarines is still deadly

KCNA/Reuters
North Korea's fleet of submarines is one of its most threatening conventional military capabilities.
The subs are largely outdated and wouldn't match up well against their US or South Korean counterparts.
But they could still pose a significant challenge in war or through low-level military aggression.
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Of all of North Korea's conventional military capabilities, the Korean People's Army (KPA) Navy's fleet of submarines stands out as one of