South Korea partially suspended a 2018 military agreement with North Korea and resumed aerial border surveillance operations on Wednesday after Pyongyang was said to have launched a military spy satellite.

"The military agreement has been partially suspended," a government spokesperson told the news agency AFP. "The remaining procedure is for the Defense Ministry to notify North Korea. But since communication lines with North Korea have been cut off, the Defence Ministry will just announce it."

Pyongyang calls launch successful

Earlier, North Korean state news agency KCNA reported that on Tuesday a rocket carrying the satellite took off from North Phyongan province and "accurately put the reconnaissance satellite 'Malligyong-1' on its orbit."

North Korean leader Kim Jong Un witnessed the launch Deutsche Welle

North Korean leader Kim Jong Un witnessed the launch, the state media reported. The successful putting of the satellite into orbit follows two earlier unsuccessful attempts.

North Korea's use of ballistic missile technology for the launch was condemned by the United Nations Secretary-General Antonio Guterres. The United States called it a "brazen violation" of UN sanctions.

Japan skeptical if spy satellite in orbit

At the same time, Japan expressed uncertainty about North Korea's claim of successfully orbiting a satellite and said it was "currently analyzing" the launch.

"The (Japanese) government at this point is not confirming whether the satellite had entered into an orbit around the Earth," chief government spokesman Hirokazu Matsuno said.

Shortly after the launch on Tuesday evening, Japan issued an evacuation alert to its residents in Okinawa in the south, which was later withdrawn.

Meanwhile, the US nuclear-powered submarine SSN Santa Fe docked in South Korea's Jeju Island, highlighting rising regional tensions.