North Korea has fired a ballistic missile, the army in Seoul announced on Wednesday (July 12th), days after Pyongyang threatened to shoot down US spy planes that violated its airspace. “North Korea fired an unidentified ballistic missile in the East Sea,” the South Korean Joint Chiefs of Staff said, using the Korean name for the Sea of ​​Japan.

Relations between the two Koreas are at their lowest. North Korean leader Kim Jong-un called his country’s nuclear power status “irreversible” last year and called for increased development of armaments, including tactical nuclear weapons. In response, Seoul and Washington pledged that Pyongyang would face a nuclear retaliation and the “end” of its current government if it decided to use atomic weapons against them.

This year, North Korea has conducted a series of weapons tests despite sanctions, including testing its most powerful intercontinental ballistic missiles (ICBMs).

On Monday, North Korea threatened to shoot down US spy planes that violate its airspace, and condemned Washington’s plan to deploy a ballistic missile submarine near the Korean peninsula. According to a spokesperson for the North Korean Ministry of Defense, the United States has “intensified its espionage activities beyond wartime levels”, referring to American spy planes which carried out several flights in July, described as “provocateurs”, over eight consecutive days.

A reconnaissance aircraft, the same source said, also “repeatedly” entered North Korea’s airspace over the Sea of ​​Japan. In a statement quoted by the state news agency KCNA, the spokesperson warned of the risk of “accident” that this type of action could have caused, such as the “fall of the United States Air Force strategic reconnaissance aircraft” in the Sea of ​​Japan.

North Korean leader Kim Jong-un’s influential sister, Kim Yo-jong, said a US spy plane violated the country’s airspace twice on Monday morning, according to a separate statement. Kim Yo-yong said Pyongyang would not respond directly to US reconnaissance activities outside the country’s exclusive economic zone, but would instead take “decisive action” if the US military crossed its military demarcation line maritime.

Washington said in April that one of its nuclear-armed ballistic submarines would visit a South Korean port for the first time in decades, without specifying the exact date. In response to North Korean weapons tests, South Korean President Yoon Suk-yeol has stepped up defense cooperation with Washington this year, holding joint military exercises.

Yoon Suk-yeol is due to attend a NATO summit in Lithuania this week, with the particular aim of strengthening cooperation with members of the Alliance in the face of threats from North Korea.

South Korea and the United States are due to begin their major annual joint military exercises, called the Ulchi Freedom Shield, in August. North Korea perceives these types of exercises as rehearsals for an invasion of its territory.