week: 8-14 December
• North Korean leader Kim Jong un claimed that his country has developed a hydrogen bomb, a step up from the less powerful atomic bomb, but outside experts were sceptical about his claim.
• A hydrogen bomb, also known as a thermonuclear bomb, uses more advanced technology to produce a significantly more powerful blast than an atomic bomb.
• North Korea conducted underground tests to set off nuclear devices in 2006, 2009 and 2013, for which it has been subject to UN security council sanctions banning trade and financing activities that aid its weapons programme.