The US has said that North Korea’s rocket launch in defiance of a UN ban has left no option but to increase pressure on Pyongyang.
North Korea was also condemned on Sunday by South Korea and Japan for launching the satellite last week, while some officials feared it was a veiled test for a long-range ballistic missile.
The criticism on Sunday comes as a US scientist said that the satellite appears to not be functioning properly.
North Korea had succeeded on Wednesday in putting an object into orbit that the communist state said was observing the earth and airing patriotic songs.
“What’s left to us is to continue to increase pressure on the North Korean regime and we are looking at how to best to do that, both bilaterally and with our partners going forward until they (North Korea) get the message. We are going to further isolate this regime,” Victoria Noland, a US state department spokeswoman, said on Monday.
The US and its allies are pushing for tighter sanctions in the UN Security Council, which already bars military trade with North Korea and has prohibited the country from conducting launches using ballistic missile technology.
It is unclear if China, North Korea’s only major ally and a key source of economic support, will endorse more restrictions.
Nuland also dismissed the notion of moving to restart six-nation talks on the North’s nuclear programme, which has been installed since 2009.
A US-based astrophysicist who monitors spaceflights has said that no signal can be detected from the the recently launched satellite.
Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics said on Monday that the satellite was clearly in orbit but that no songs could be heard.
“To the best of our knowledge, the satellite isn’t operating,” he said. “It’s definitely up there and it’s whizzing around, but it’s just not feeling very well.”
McDowell said it was unclear whether the satellite – called the Kwangmyongsong-3 – worked initially and that it remained possible that it was transmitting at a level too faint for detection.
But in another sign of trouble, McDowell said that the satellite was fluctuating in brightness. That means that the sun is shining at different angles and the satellite is not pointing down at the Earth as it should.
Even if not functioning, the satellite remains in orbit. The commercial site www.n2yo.com on Monday tracked the satellite as orbiting at least 505km above Earth, in line with North Korean statements.
“These things are hard to calculate, but roughly speaking, an object of that density at that height is going to stay up for a few years,” McDowell said.
The state-run Korean Central News Agency last week quoted a scientist saying that the technology was “flawless” and that the satellite was broadcasting “Song of General Kim Il-Sung” and “Song of General Kim Jong-Il,” references to the state’s first two leaders.
The launch came days before the anniversary of Kim Jong-Il’s death. His young son, Kim Jong-Un, succeeded him as leader of the regime, which conceded that an attempted launch in April malfunctioned.
George Little, a Pentagon spokesman, said that the US was “still assessing” the North Korean satellite and that he was unaware of any danger posed.