The United States on Monday warned North Korea not to fire a long-range missile, saying it would worsen tensions after the communist state's nuclear test.
State Department spokesman Robert Wood said that a launch would be a "clear violation" of UN Security Council resolution approved after Pyongyang's first nuclear test in 2006.
"The North, frankly, just needs to end this provocative type of behavior. It's only inflaming tensions in the region," Wood said.
"We want to see the North live up to its international obligations," Wood said.
US and South Korean defense officials say there are signs that North Korea is preparing to fire an intercontinental ballistic missile, in what would be its second such launch in as many months.
The development comes as the UN Security Council meets to discuss a response to last week's nuclear test.
Secretary of State Hillary Clinton on Sunday spoke by telephone with Russian Foreign Minister Sergei Lavrov and Chinese Foreign Minister Yang Jiechi ahead of the deliberations in New York, Wood said.
"I think it's very clear that we are all on the same page with regard to the need to take very strong measures against North Korea," Wood said.