SEOUL, South Korea — North Korea launched a ballistic missile toward the sea on Wednesday, its neighbors said, the second such weapons testing activity in less than a week.

The series of launch events was most likely a protest of the upcoming Korea-U.S. military drills that North Korea views as an invasion rehearsal.

South Korea’s Joint Chiefs of Staff said it detected the launch from North Korea’s eastern coastal Wonsan area in the direction of the North’s eastern waters around 6 a.m.

South Korea’s military said it boosted its surveillance posture and that Seoul was closely exchanging information on the launch with Washington and Tokyo.

Japan’s Defense Ministry said it also spotted a suspected ballistic missile launch from North Korea. It said it didn’t detect the weapon reaching Japan’s exclusive economic zone, suggesting it was believed to have fallen farther away from the Japanese coast.

The latest launch came two days after South Korea and the United States announced they will kick off their annual large-scale military drills next week to beef up readiness against North Korean threats.

The Ulchi Freedom Shield training is to start on Monday for an 11-day run. Its scale will be similar to that of previous years, with 18,000 South Korean soldiers taking part, according to South Korea’s military.

North Korea has previously responded to the training and other major South Korea-U.S. military exercises with provocative weapons tests and harsh rhetoric. North Korea calls such drills a practice to attack the country that forces it to bolster its nuclear arsenal, though the U.S. and South Korea have repeatedly said their training is defensive in nature.

On Aug. 6, South Korea, the U.S. and Japan detected the launch of a short-range ballistic missile from North Korea in what was the North’s first ballistic weapons testing activity since late June. North Korea didn’t confirm the reported launch, though it usually releases details of weapons tests a day later.

North Korea has been engaging in a run of weapons tests since its leader Kim Jong Un’s high-stakes diplomacy with U.S. President Donald Trump fell apart in 2019 because of disputes over international economic sanctions on North Korea.