Seoul, South Korea (afp) — North Korea fired two short-range ballistic missiles but one launch failed, South Korea’s military said Monday, a day after Pyongyang warned of “fatal consequences” following major joint exercises in the South.

South Korea’s Joint Chiefs of Staff (JCS) said the military had detected two launches, the first at 5:05 a.m. (2005 GMT) and the second around 10 minutes later.

“The short-range ballistic missile launched at around 05:05 flew approximately 600 kilometers,” it said, adding the second one traveled 120km.

JCS spokesperson Lee Sung-jun said the second missile appeared to fly abnormally in an early stage of flight, adding that if it had exploded in mid-air, its trajectory indicates debris could have landed over North Korea.

Seoul’s military has “strengthened surveillance and vigilance in preparation for further launches,” JCS said in a statement.

North Korea is accused of breaching arms control measures by supplying weapons to Russia to use in its war in Ukraine, and Russian President Vladimir Putin held a summit with leader Kim Jong Un in Pyongyang in June in a show of unity.

The JCS’ Lee declined to comment when asked whether the North’s latest launch could have been a test of missiles intended for delivery to Russia.

The launch also comes after Pyongyang on Sunday denounced joint military exercises by South Korea, Japan and the United States, calling them an “Asian version of NATO” and warning of “fatal consequences.”

The three-day “Freedom Edge” drills, which ran from Thursday to Saturday last week, included preparation in ballistic missile and air defenses, anti-submarine warfare and defensive cyber training.