The apparent resumption of activity at North Korea’s Yongbyon nuclear facility was not a surprising move, three former South Korean unification ministers under progressive administrations said on Tuesday at a forum hosted by the Ministry of Unification (MOU).

The former ministers’ remarks come after the International Atomic Energy Agency (IAEA) said in a report last week that there were “deeply troubling” indications that North Korea had resumed activity at its primary nuclear site for the first time in three years.