Monday marked the beginning of joint military exercises between the United States, Japan, and South Korea, while North Korea continued to threaten their alliance.
Monday marked the start of the United States and its allies’ first combined naval anti-submarine exercise in six months. According to South Korea’s defense ministry, the aircraft carrier USS Nimitz participated in the exercise alongside destroyers from all three countries.
Submarine-launched missiles are more difficult to track than ground- or even air-launched missiles due to the unpredictability of the launch location.
North Korea warned of reprisal before Monday’s military exercises, claiming it was not engaging in “empty talk.”

The rhetoric was contained in a statement issued by the state-run Korean Central News Agency (KCNA), which lambasted South Korea and the United States for participating in the 11-day Freedom Shield drill last month.
The statement added, “Their war fever is reaching its peak as Ssangyong, a combined landing exercise, begins.”
It continued, “This recalls the people and army of the [Democratic People’s Republic of Korea] of June 1950, when they were subject to war calamity, and further heightens their alertness.”
Kim Jong Un urged his nation to be prepared to launch a nuclear attack as a deterrent against conflict last month. His remarks followed a spate of missile launches in which North Korea tested its capabilities.
North Korean media described Kim as saying, “The DPRK’s nuclear force will resolutely deter, control, and manage the enemy’s reckless acts and provocations with its high war preparedness, and will carry out its vital job without hesitation in the event of any unwelcome situation.”