A suspected hypersonic missile launched by North Korea exploded in flight on Wednesday, South Korea’s military said, a development that comes as North Korea is protesting the regional deployment of a U.S. aircraft carrier for a trilateral military drill with South Korea and Japan.

The missile launched from the North's capital region around 5:30 a.m. was aimed toward the North’s eastern waters before the failure, South Korea’s Joint Chiefs of Staff said in a statement.

The Joint Chiefs of Staff later said the missile blew up as it was flying off the North’s eastern coastal city of Wonsan. The missile fragments were scattered in the water, up to 250 kilometers (155 miles) from the launch site. No damages were immediately reported.

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The Joint Chiefs of Staff suspected the weapon was a solid-fueled hypersonic missile and the test was aimed at improving its capacity. The launch generated more smoke than normal launches, possibly because of an engine fault, the Joint Chiefs of Staff said.

The contents of the background briefing to South Korean journalists were shared with foreign media.

The U.S. Indo-Pacific Command said it condemned the launch and the U.S. commitments to the defense of South Korea and Japan “remain ironclad.”

In a trilateral phone call, senior diplomats from South Korea, the U.S. and Japan condemned the North’s missile launch as a violation of U.N. Security Council resolutions and a threat to international peace. They agreed to maintain close three-way coordination, according to South Korea’s Foreign Ministry.

Since 2021, North Korea has performed a series of hypersonic missile tests in an apparent bid to acquire an ability to penetrate its rivals’ missile defense shields. But foreign experts question if North Korean hypersonic vehicles have proved their desired speed and maneuverability during test-flights. In recent years, North Korea has also been pushing to develop more weapons with solid propellants, Such propellants make launches harder to detect than liquid-propellant missiles, which must be fueled before liftoff.

The launch also came as the rival Koreas are engaged in Cold War-style, psychological campaigns such as balloons and loudspeaker broadcasts.

South Korea said that North Korea floated huge balloons carrying trash across the border Tuesday night for its sixth such campaign since late May. About 100 North Korean balloons with bags of paper waste reportedly fell on South Korean territory.

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Incheon International Airport, South Korea's biggest and about an hour's drive from the inter-Korean border, suspended takeoffs and landings for three hours early Wednesday in the second such disruption since the North's balloon activities began on May 28, according to South Korean aviation authorities.

North Korea calls its balloon launches a tit-for-tat response to South Korean activists flying political leaflets via their own balloons. On June 9, South Korea briefly restarted propaganda broadcasts from its border loudspeakers for the first time in years in response. South Korea’s military said Monday said it was ready to turn on its loudspeakers again.

The USS Theodore Roosevelt arrived in South Korea on Saturday and South Korean President Yoon Suk Yeol boarded the aircraft carrier on Tuesday — the first sitting South Korean president to board a U.S. aircraft carrier since 1994.

Yoon told American and South Korean troops on the carrier that their countries’ alliance is the world’s greatest and can defeat any enemy. He said the U.S. carrier is to leave Wednesday for the South Korea-U.S.-Japan drill, dubbed “Freedom Edge.” The training is aimed at sharpening the countries’ combined response in various areas of operation, including air, sea and cyberspace.

North Korea’s vice defense minister, Kim Kang Il, on Monday called the U.S. aircraft carrier’s deployment “reckless” and “dangerous.” North Korea has previously called major U.S.-South Korean drills invasion rehearsals and reacted with missile tests.

Seoul officials said the upcoming South Korea-U.S.-Japan training is meant to strengthen the three countries’ response capabilities against North Korea’s evolving nuclear threats at a time when the North is advancing its military partnerships with Russia.

During a summit in Pyongyang last week, North Korean leader Kim Jong Un and Russian President Vladimir Putin signed a deal requiring each country to provide aid if attacked and vowed to boost other cooperation. Observers say the accord represents the strongest connection between the two countries since the end of the Cold War.

The United States and its partners believe North Korea has been providing Russia with much-needed conventional arms for its war in Ukraine in return for military and economic assistance.

North Korea’s reported missile launch is its first weapons demonstrations since Kim Jong Un on May 30 supervised the firing of nuclear-capable multiple rocket launchers to simulate a preemptive attack on South Korea.

Since 2022, North Korea has sharply increased the pace of weapons tests to increase its nuclear attack capabilities to cope with what it calls an deepening U.S. military threat. Foreign experts say North Korea eventually aims to use its larger nuclear arsenal to wrest greater concessions from the U.S. when diplomacy resumes.