On October 22, the South Korean military said North Korea had launched many objects believed to be short-range ballistic missiles into the eastern sea.
The launch took place just a week before South Korea hosted the Asia-Pacific Economic Cooperation (APEC) Summit, with the participation of South Korean President Lee Jae Myung, US President Donald Trump and Chinese President Xi Jinping.
The South Korean Joint Chiefs of Staff confirmed that the missiles were launched from near Pyongyang, flying northeast into the sea.
The agency is coordinating data sharing with the US and Japan to assess the situation. The South Korean military said the launch could be part of a series of tests to demonstrate military power ahead of a major international event.
Japan said the launch did not affect its security. Prime Minister Sanae Takaichi affirmed that Tokyo is maintaining real-time contact with Washington to monitor developments.
This is the first time North Korea has tested a ballistic missile since May, when the country fired many short-range missiles from the east coast.
Experts say the latest action could be Pyongyang's political message to the region as the APEC summit is seen as an important opportunity for the world's top leaders to discuss security and economic issues.
Previously, North Korea showed off a new intercontinental ballistic missile model at a parade on October 10 to celebrate the 80th anniversary of the founding of the DPRK Labor Party.
North Korea's launch right before the summit has further strained the regional atmosphere. Observers said that South Korea, the US and Japan will take advantage of the upcoming meeting to issue a unified response and discuss steps to maintain stability and prevent the escalation of the conflict on the Korean peninsula.