Ballistic missile launch comes hours after Pyongyang threatened "fiercer" military responses against US moves to bolster its military presence in the region.
Military leaders are releasing thousands, including an ex-British envoy, a Japanese journalist and an Australian economics adviser from prison, officials and local media say.
The APEC meeting comes on the heels of the G20 summit in Bali where countries unanimously adopted a declaration saying most members condemned the war in Ukraine, but that also acknowledged some countries saw the conflict differently.
In their first-ever meeting, China's President Xi Jinping tells Italian Prime Minister Giorgia Meloni that he hoped Italy would play an important role in helping the EU's policy towards China remain "positive".
The country's National Security Committee said a group of seven people was trying to organise large-scale riots and planning to attack administrative buildings and law enforcement offices with arms and projectiles.
Russians Sergey Dubinskiy and Igor Girkin, as well as Ukrainian Leonid Kharchenko, were found guilty of causing the crash that killed 298 civilians in 2014.
