Seoul, South Korea (CNN) North Korea fired two missiles over the weekend from a submarine in waters off its east coast and vowed to mount “tough resistance” to the US and South Korea’s biggest joint military exercises in years starting on Monday.

Pyongyang’s official KCNA news agency said the “strategic cruise missiles” were launched Sunday morning from the “8.24 Yongung” submarine in the Sea of ​​Japan, also known as the East Sea in Korea. The same vessel was used to test North Korea’s first submarine-launched ballistic missile in 2016. CNN previously reported.

Sunday’s launches came about 24 hours before Washington and Seoul began their spring joint military exercises on Monday, the biggest war games the two allies have held in five years.

The 11-day Freedom Armor exercise will “combine elements of ‘live exercises’ with creative simulations,” US Forces Korea (USFK) said in an earlier statement.

KCNA reported Monday that North Korea reiterated that it would take “the strongest resistance against the worst plots by the United States and its supporters.”

Pyongyang has issued several warnings against the planned drills, saying it “observes the enemy’s every move and takes a corresponding and very powerful and huge countermeasure against every move of the enemy against us,” said Kim Yo Jong, sister of North Korean leader Kim. Jong Un said last month.

Tit for tat exercises

North Korean missile launches and fiery rhetoric escalate as Washington and Seoul hold joint military exercises.

South Korea’s Joint Chiefs of Staff (JCS) said earlier on Sunday that North Korea fired at least one unidentified missile from a submarine near the port city of Sinpo in South Hamgyong Province.

KCNA said the missiles flew for more than an hour, traveling at about 1,500 kilometers (932 miles) per hour, making eight patterns before “precisely” hitting the target.

KCNA reported that the Central Military Commission of the Workers’ Party of Korea “expressed satisfaction” after the exercise.

JCS said US and South Korean intelligence officials are investigating the incident.

Thursday’s launch came three days after North Korea At least six short-range missiles were fired Into the Yellow Sea.

State media reported last week that Kim Jong Un said artillery units should be ready for two missions: “first to prevent war and second to take the initiative in war by intensifying various simulated exercises for real war.”

Pyongyang is carrying out its winter training and intelligence officials in the US and South Korea are monitoring it, a South Korean defense ministry spokesman said on Thursday.

‘Only the Beginning’

The US and South Korean air forces are also conducting their regular air exercises.

Last week, a US B-52 bomber was intercepted by South Korean fighter jets after it flew into the South’s air defense identification zone, the USFK said on Monday.

The US-South Korea drills are expected to be the largest in years, as they scaled back such military displays in 2017 when then-US President Donald Trump tried to offer North Korea an opportunity to negotiate. Its long-range missile and nuclear weapons programs.

That opening has long been closed, with North Korea conducting missile tests last year while promising to upgrade its nuclear program to weaponize missiles.

The North’s missile tests have slowed in 2023, but tensions remain high on the Korean Peninsula.

Analysts see little reason to think things will cool down.

“This is just the beginning of a series of provocative tests by North Korea,” Leif-Erik Easley, a professor at Ewha Women’s University in Seoul, said of the missile strikes on Thursday.

“Pyongyang is ready to respond aggressively to major U.S.-South Korea defense exercises and summits between President Yoon, (Japanese) Prime Minister (Fumio) Kishida and (U.S.) President (Joe) Biden.”

“The Kim regime could order the launch of long-range missiles, attempt to launch a spy satellite, demonstrate a solid-fuel engine, and possibly conduct a nuclear test,” Easley said.