South Korea Test-Flies Its First Homegrown Hypersonic Weapon as North Korea Tensions Climb

SEOUL, South Korea — South Korea flight-tested its first domestically developed hypersonic weapon on Thursday, a system designed to fly at least five times the speed of sound and slip past missile defenses. Seoul says the test brings it closer to what it calls game-changing conventional weapons.

According to a statement from President Lee Jae Myung's office, the weapon separated from its booster rocket at the planned altitude, then descended and maneuvered both vertically and horizontally before hitting a test target. The statement did not say where the test took place. Once developed, it said, the weapon would be able to strike key targets by surprise in the "Korean Peninsula theater of operations." Lee attended the flight and called it a major step in strengthening the country's conventional defense capabilities. He also inspected the Hyunmoo-5, the country's most powerful ballistic missile, the same day.

North Korea had not responded by the time the test was reported. Last week, on Oct. 3, it launched what it called a hypersonic intermediate-range missile that it said flew more than 1,000 kilometers (621 miles). Japan said the missile landed outside its exclusive economic zone. South Korea said it detected a flight of more than 700 kilometers (435 miles), and Japan's Defense Ministry assessed about 680 kilometers (422 miles). Kim Yo Jong, the sister of leader Kim Jong Un, said the differing estimates showed the two U.S. allies cannot properly track such a missile and so could not intercept it.

Tensions between the Koreas have climbed in recent weeks. Three South Korean soldiers were injured last month in land mine explosions near the heavily armed border. The South's military and the U.S.-led United Nations Command concluded the devices were planted by North Korea, which has denied responsibility and ridiculed Seoul's demands for an apology. North Korea has also stepped up weapons testing as Kim expands the country's nuclear program and takes an increasingly hard line toward the South.

The tensions are a political setback for Lee, who favors engagement with Pyongyang and has tempered his rhetoric toward the North even as public anger grows over the mine blasts. At the same time, he has called for strengthening South Korea's conventional forces and reducing reliance on the United States. Lee said Thursday that South Korea "must secure our security through our own strength." The U.S. unilaterally decided in August to scale back a major military exercise with the South, with President Donald Trump citing his "very good relationship" with Kim.

Kim has so far rebuffed Trump's calls to revive the diplomacy that broke down in 2019. His government demands that Washington abandon what it calls a "hostile" policy toward Pyongyang and drop its demand for denuclearization as a precondition for talks. With neither side willing to move first, both Koreas are now fielding weapons designed to defeat the other's defenses.