SEOUL, South Korea (AP) — North Korea added to its recent barrage of weapons demonstrations by launching four ballistic missiles into the sea on Saturday as the United States sent two supersonic bombers over Korea of the South in a duel of military might that underlined rising tensions in the region.

South Korea’s Joint Chiefs of Staff said the four short-range missiles fired from a western coastal area of ​​North Korea around noon flew about 130 kilometers (80 miles) towards the western sea of ​​the country.

The North has tested more than 30 missiles this week, including an intercontinental ballistic missile on Thursday that triggered evacuation alerts in northern Japan, and flew scores of warplanes inside its territory in an angry reaction to a massive combined air exercise between the United States and South Korea.

The South Korean military said two B-1B bombers trained with four US F-16 fighter jets and four South Korean F-35 jets during the final day of joint army exercises. “Vigilant Storm” air which ends on Saturday. It was the first time since December 2017 that the bombers had been deployed to the Korean Peninsula. The exercise involved around 240 combat aircraft, including advanced F-35 fighter jets from both countries.

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On Friday night, North Korea’s foreign ministry described the country’s military actions this week as an appropriate response to the exercise, which it called “military confrontation hysteria” by the United States. He said North Korea would respond with the “toughest reaction” to any attempt by “hostile forces” to encroach on its sovereignty or security interests.

South Korea’s Joint Chiefs of Staff said the B-1Bs’ participation in the joint exercises demonstrated the allies’ willingness to “respond sternly” to North Korean provocations and the American commitment to defend its ally with all the range of its military capabilities, including nuclear.

B-1B overflights had been a familiar show of force during past periods of tension with North Korea, including the North’s provocative run in nuclear and long-range missile tests in 2017. But the overflights had been halted in recent years as the United States and South Korea halted large-scale exercises to support the former Trump administration’s diplomatic efforts with North Korea and due to the COVID-19 pandemic.

Allies resumed large-scale training this year after North Korea ramped up its weapons testing at a record pace, exploiting a split in the UN Security Council over Russia’s war on Ukraine. as a window to accelerate the development of armaments.

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North Korea hates such point-blank displays of US military power. The North continued to describe the B-1B as a “nuclear strategic bomber” although the aircraft switched to conventional armament in the mid-1990s.

Vigilant Storm was originally scheduled to end on Friday, but the allies decided to extend the training until Saturday in response to a series of North Korean ballistic launches on Thursday, including an ICBM that triggered evacuation alerts and stopped trains in northern Japan.

Thursday’s launches came after the North fired more than 20 missiles on Wednesday, the most in a single day. The launches came after senior North Korean military official Pak Jong Chon issued a veiled threat of nuclear conflict with the United States and South Korea over their joint exercises, which the North says are rehearsals for a possible invasion.

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South Korea also dispatched around 80 military aircraft on Friday after tracking around 180 flights of North Korean warplanes inside North Korean territory. The South’s Joint Chiefs of Staff said North Korean warplanes had been detected in various areas inland and along the country’s east and west coasts, but did not come particularly close. from the Korean border. The South Korean military spotted about 180 flight tracks from 1 p.m. to 5 p.m., but it was not immediately clear how many North Korean planes were involved and whether any may have flown more than once.

In Friday’s statement attributed to an unidentified spokesperson, North Korea’s foreign ministry said the United States and South Korea had created an “unstable atmosphere” in the region with their military exercises. He accused the United States of mobilizing its allies in a campaign using sanctions and military threats to pressure North Korea to disarm unilaterally.

“Sustained provocation will necessarily be followed by sustained counter-action,” the statement said.

North Korea has launched dozens of ballistic missiles this year, including several ICBMs and an intermediate-range missile flown over Japan. South Korean officials say there are indications North Korea may detonate its first nuclear test device since 2017. Experts say North Korea is trying to force the United States to agree to it as a nuclear power and seeks to negotiate economic and security concessions from a position of strength.