South Korea, the United States and Japan shared information about North Korea's launch of what it claimed to be a military spy satellite, South Korea's Joint Chiefs of Staff said Wednesday.

"We immediately detected, tracked and monitored the launch, and shared related information among South Korea, the United States and Japan, and we are comprehensively analyzing detailed specifications," the JCS said in a message to reporters.

North Korea said it successfully launched a space rocket carrying a military reconnaissance satellite southward from its west coast late Tuesday, after two failed attempts in May and August, respectively.

The JCS said that the three countries had an Aegis destroyer equipped with radar with a detection range of over 1,000 kilometers on standby in the sea areas designated by each country for joint detection and tracking among the three countries.

A military official said that it was not a real-time sharing of information as such a system has not been initiated yet. The three countries plan to start operating the real-time three-way information sharing system next month.

The JCS has yet to confirm whether the North's launch made the entry into orbit.

"North Korea said it was successful, but we can confirm whether it has entered properly after the satellite circles the orbit a few times," a military official said.

The JCS vowed to maintain the capability and readiness to "overwhelmingly respond" to any provocation by the North under the allies' solid combined defense posture, while keeping a close eye on the North's various activities.

Meanwhile, US Assistant Secretary of Defense for Indo-Pacific Security Affairs Ely Ratner held separate phone talks with South Korea's Deputy Defense Minister for Policy Heo Tae-keun and Japan's Director-General for Defense Policy Koji Kano to discuss the North's launch, according to the Pentagon.

The officials "strongly" condemned the North's launch as a violation of multiple UN Security Council resolutions, the Pentagon said in a press release. Ratner reaffirmed America's "ironclad" extended deterrence commitment to South Korea and Japan, it added.

Extended deterrence refers to the US' commitment to using the full range of its military capabilities, including nuclear, to defend its allies. (Yonhap)