KIM TONG-HYUNG SEOUL, South Korea — South Korea flight-tested on Thursday its first domestically developed hypersonic weapon, designed to fly at least five times the speed of sound and evade missile defense systems, bringing Seoul closer to what it says could be game-changing weapons capabilities.

There was no immediate response from North Korea, which last week tested its own hypersonic missile that landed in the waters near Japan.

South Korean President Lee Jae Myung attended the test, saying it’s a major step in strengthening the country’s conventional defense capabilities, according to a statement. It did not elaborate where the test took place.

The statement said the weapon separated from its booster rocket at the planned altitude, then descended and maneuvered both vertically and horizontally before hitting a test target. It said once developed, the weapon would be able to strike key targets by surprise in the “Korean Peninsula theater of operations.”Lee stressed that South Korea “must secure our security through our own strength,” and also inspected the country’s most powerful Hyunmoo-5 ballistic missile on Thursday, his office said. It did not mention any direct comments by Lee on the North.

Tensions between the Koreas have increased in recent weeks after three South Korean soldiers were injured in land mine explosions last month near the heavily armed inter-Korean border.

The South’s military and the U.S.-led United Nations Command concluded the blasts were caused by devices planted by North Korea, which has denied responsibility and ridiculed the South’s demands for an apology.

North Korea has also stepped up weapons testing activity as its leader Kim Jong Un expands his military nuclear program while taking an increasingly hard line toward Seoul.

Kim has so far rebuffed U.S. President Donald Trump’s calls to revive their diplomacy that broke down in 2019, with his government demanding that Washington abandon its “hostile” policy toward Pyongyang and drop demands for its denuclearization as a precondition for talks.

The tensions have been a setback for Lee, who favors engagement with North Korea and has tempered his rhetoric toward the North even as public anger grows over the mine blasts.

Lee has also called for strengthening South Korea’s conventional defense capabilities while reducing its reliance on the United States, which unilaterally decided to scale back a major military exercise with the South in August, with Trump citing his “very good relationship” with Kim.

In its latest weapons test on Oct. 3, North Korea launched what it described as a hypersonic intermediate-range missile that it said flew more than 1,000 kilometers (621 miles). Japan said the missile landed in waters outside of its exclusive economic zone.

South Korea said it detected the missile flying more than 700 kilometers (435 miles), while Japan’s Defense Ministry said it assessed that the missile flew about 680 kilometers (422 miles).

Kim Yo Jong, the powerful sister of the North Korean leader, claimed the differing flight estimates by the two U.S. allies showed they are incapable of properly tracking such a missile during its flight and would therefore not be able to intercept it.