SEOUL, South Korea (AP) — North Korea launched a long-range rocket in a southern direction on Thursday, South Korea’s military said, in the North’s likely second attempt to put a spy satellite into orbit.

South Korea’s Joint Chiefs of Staff said in a statement that the launch involved what the North called “a space launch vehicle.”

It said South Korea detected the rocket flying above international waters off the Korean Peninsula’s west coast after its liftoff at the North’s northwestern Tongchang-ri area at 3:50 a.m.

The site is where North Korea’s main space launch center is located. The North made its first, failed launch of a spy satellite there in late May.

South Korea’s military said it has bolstered its surveillance posture and maintains a readiness in close coordination with the United States.

On Tuesday, Japan’s coast guard said North Korean authorities notified it about a plan to launch a satellite at some time from Aug. 24 through Aug. 30. Coast guard spokesperson Hiromune Kikuchi said the notice didn’t specify the type of satellite, but that he believed it would be similar to North Korea’s May launch.

On May 31, a North Korean rocket carrying a spy satellite plunged into the sea soon after liftoff, posing a setback to leader Kim Jong Un’s push to establish a space-based surveillance system to better monitor the U.S. and South Korea. North Korea had since vowed to make a second attempt.

After its failed first launch, North Korea made an unusually quick admission of failure after its newly developed Chollima-1 rocket lost thrust between launch stages and crashed into the sea on May 31. The North’s ruling party leadership described the failed launch as a serious setback in the country’s efforts to bolster its military capabilities amid tensions with rivals.

North Korea’s neighbors and the United States condemned the May launch for raising tensions and violating U.N. Security Council resolutions that banned the country from using ballistic missile technology.

Thursday’s launch came three days after the U.S. and South Korean militaries kicked off annual military drills that North Korea calls an invasion rehearsal.

North Korea’s official Korean Central News Agency said the U.S.-South Korean exercises are increasing the danger of a nuclear war on the Korean Peninsula. It said the current situation is compelling North Korea to take “offensive, overwhelming” steps, but didn’t elaborate.