“The Yongbyon site is thought to be its main nuclear facility. The North has pledged several times to halt operations there and even destroyed the cooling tower in 2008 as part of a disarmament-for-aid deal.
But in March 2013, after a war of words with the US and with new UN sanctions over the North’s third nuclear test, it vowed to restart all facilities at Yongbyon.
However, the US never believed Pyongyang was fully disclosing all of its nuclear facilities – a suspicion bolstered when North Korea unveiled a uranium enrichment facility at Yongbyon (purportedly for electricity generation) to US scientist Siegfried Hecker in 2010.
Mr Hecker’s 2010 visit and subsequent report remains the most recent and reliable account of the complex.
In April 2015 a US think tank said satellite pictures taken in early 2015 suggested the reactor at Yonbyon may have been restarted.”