Seoul, South Korea (CNN)North Korea launched two missiles from a submarine in waters off its east coast over the weekend, according to state media, and vowed to take "the toughest counteraction" against the largest joint military drills by the United States and South Korea in years that kick off Monday.
Pyongyang's official KCNA news agency said the "strategic cruise missiles" were launched on Sunday morning from a "8.24 Yongung" submarine in the Sea of Japan, also known in Korea as the East Sea. The same vessel was used to test North Korea's first submarine-launched ballistic missile in 2016, CNN previously reported.
The launches Sunday came some 24 hours before Washington and Seoul initiated their springtime joint military exercise on Monday, the biggest war games the two allies have put on in five years.
The 11-day Freedom Shield exercise "will integrate elements of 'live exercises' with constructive simulations," US Forces Korea (USFK) said in an earlier statement.
North Korea reiterated that it will take "the toughest counteraction against the most vicious plots of the US and its followers," KCNA reported Monday.
Pyongyang has issued multiple warnings against the scheduled drill, noting that it is watching "every movement of the enemy and take corresponding and very powerful and overwhelming counteraction against its every move hostile to us," Kim Yo Jong, the sister of North Korean leader Kim Jong Un, said last month.
Tit for tat drills
North Korean missile launches and fiery rhetoric tends to spike when Washington and Seoul hold joint military drills.
South Korea's Joint Chiefs of Staff (JCS) said earlier Sunday that North Korea fired at least one unidentified missile from a submarine near the port city of Sinpo in the South Hamgyong province.
KCNA claimed the missiles flew for over an hour, traveling roughly 1,500 kilometers (932 miles) per hour and performing figure-of-eight shaped patterns before "precisely" hitting a target.
The Central Military Commission of the Workers' Party of Korea "expressed satisfaction" after the drill, KCNA reported.
The US and South Korean intelligence authorities are analyzing the incident, JCS said.
The launch took place three days after North Korea on Thursday fired at least six short-range missiles into the Yellow Sea.
State media reported last week that Kim Jong Un said the artillery units should be prepared for two missions, "first to deter war and second to take the initiative in war, by steadily intensifying various simulated drills for real war."
Pyongyang is conducting its winter training and intelligence authorities in the US and South Korea are monitoring it, South Korea's Defense Ministry spokesman said Thursday.
'Likely only the beginning'
US and South Korean air forces have also been conducting their own regular air exercises.
Last week, a US B-52 bomber was escorted by South Korean fighter jets as it flew into the South's air defense identification zone, USFK said Monday.
The US-South Korea exercises are expected to be the largest the two allies have put on in years, since they scaled back such military displays in 2017 when then-US President Donald Trump tried to offer an opening for North Korea to negotiate an end to its long-range missile and nuclear weapons programs.
That opening has long since closed, with North Korea last year conducting a record number of missile tests while pledging to develop its nuclear program to arm the missiles.
The North's missile testing has slowed in 2023, but tensions on the Korean Peninsula remain high.
Analysts see little reason to think things will cool down.
"This is likely only the beginning of a series of provocative tests by North Korea," Leif-Eric Easley, a professor at Ewha Womans University in Seoul, said of Thursday's missile firings.
"Pyongyang is poised to respond aggressively to major US-South Korea defense exercises, as well as to President Yoon's upcoming summits with (Japanese) Prime Minister (Fumio) Kishida and (US) President (Joe) Biden."
"The Kim regime may order missile firings of longer ranges, attempt a spy satellite launch, demonstrate a solid-fuel engine, and perhaps even conduct a nuclear test," Easley said.