At an emergency cabinet meeting following the launch on Tuesday evening, Seoul vowed to resume surveillance operations along the high-security border between the two countries, which were suspended in 2018 to reduce tensions during a détente that led to since-collapsed nuclear disarmament talks.
The decision was approved by Yoon Suk Yeol, the South Korea president, from London, where he is conducting a state visit.
It was prompted by the North’s decision to defy a United Nations ban on conducting satellite launches and its pledge to continue to build its space-based surveillance system.
Pyongyang’s move was immediately condemned by the United States and its allies, amid concerns that such launches provide cover for tests of illegal missile technology.
On Wednesday, Kim Jong-un, the North Korean leader, viewed photographs of the US military air base in Guam, state media reported.
The North’s claim could not be immediately independently confirmed and observers doubt whether the satellite is advanced enough to perform military reconnaissance.
Announcing Seoul’s response to suspend part of the 2018 military agreement, Han Duck-soo, the South Korean prime minister, said that the North was clearly demonstrating that it had no will to abide by the pact or build trust.
The suspension will allow Seoul to restore reconnaissance operations in the area around the so-called Military Demarcation Line separating the two countries.
“Our military’s ability to identify threatening targets and its response posture will be greatly enhanced,” Mr Han said, adding that such a measure is vital for national security.
The “Chollima-1” rocket carrying the satellite blasted off on Tuesday night from North Pyongan province, flew along its designated path and “accurately put the reconnaissance satellite ‘Malligyong-1’ on its orbit,” the state-run news agency KCNA reported.
It added that Mr Kim was on hand to witness the launch, and congratulated the scientists and technicians at the National Aerospace Technology Administration who were behind the mission.
“The launch of [this] reconnaissance satellite is a legitimate right of the DPRK [North Korea] for strengthening its self-defensive capabilities and it will make a significant contribution to definitely ramping up the war preparedness of the armed forces,” said the newswire.
The United States quickly condemned the launch as a “brazen violation” of UN sanctions and said that it could destabilise the region.
South Korean officials said that the latest launch probably incorporated technical assistance from Moscow as part of a growing partnership that has seen North Korea allegedly send millions of artillery shells to Russia.
Russia and North Korea have denied such arms deals but are publicly promising deeper cooperation.
North Korea’s previous efforts to put a spy satellite into orbit in May and August both failed.
Seoul, Tokyo and Washington had repeatedly warned Pyongyang not to proceed with another launch, which would violate successive rounds of UN resolutions.
“Even if they call it a satellite, the launch of an item that uses ballistic missile technology is clearly a violation of the relevant United Nations resolutions,” Fumio Kishida, the Japanese prime minister, said, adding that he condemned the launch “in the strongest possible terms”.
Ahead of the blast-off, China’s foreign ministry blamed the “frequent appearances of US strategic bombers and aircraft carrier battle groups” for stoking tensions in the region.
“China urges relevant parties to face up to the crux of the Korean Peninsula issues, stop engaging in confrontation and pressuring, take concrete steps to pursue a political settlement of those issues and maintain peace and stability on the Peninsula,” said spokesman Mao Ning.
Leif-Eric Easley, a professor at Ewha University in Seoul, offered a cautious assessment of the North’s claims.
“State-controlled media claims of a successful launch do not mean the satellite will actually perform meaningful reconnaissance functions,” he said.
He added that the surveillance drone operations Seoul may soon start along the border zone “should produce more useful intelligence than North Korea’s rudimentary satellite programme”, although “Pyongyang will likely use South Korean drone flights as an excuse for further military provocations”.