America and key Asian allies will seek United Nations Security Council action if North Korea launches a long-range rocket this month, the US State Department said.
Pyongyang plans the launch between December 10 and 22 in defiance of a UN ban.
Washington sees such launches as veiled tests of missiles designed to strike the United States, but North Korea says it is trying to put a communications satellite into orbit.
US envoy for North Korea policy Glyn Davies met his Japanese and South Korean counterparts in Washington on Tuesday.
State Department spokesman Mark Toner said they were calling for the North to comply with its international obligations and refrain from a launch using ballistic missile technology - although he conceded there was no sign Pyongyang was willing to listen.
"All three countries also affirmed that if North Korea does, in fact, proceed with a launch, we would seek action by the UN Security Council, but I'm not going to get into what that might be," Mr Toner told a news briefing, although he added that "there's always ways to toughen enforcement of sanctions".
The council condemned a failed North Korean launch in April and ordered assets of three North Korean state companies linked to financing, exporting and procuring weapons and missile technology to be seized.
Two US officials said yesterday that the US Navy had begun moving several ships into the western Pacific in preparation for the planned launch of a long-range rocket by North Korea.
The officials said shifting the ballistic missile defence capable ships into the region was part of a routine process aimed at reassuring US allies there.
They said no more than three or four ships were being repositioned.
It is the third time in six years that the security council has imposed sanctions against North Korea. It blacklisted eight entities - six trading companies, a bank and the General Bureau of Atomic Energy - and five individuals after nuclear tests in 2006 and 2009.
Under security council resolutions, nations are also barred from buying or selling weapons with North Korea, a key source of revenue for its authoritarian regime.
Winning the support of Russia and China, North Korea's main ally and economic partner, will be key to the world body's endorsing any further punishments.