By Peter Foster in Beijing
North Korea, which has informed international agencies of its plan to fire the missile between April 4 and 8, says the launch is a "satellite test" which it is entitled to make under international law.
Japan has threatened to shoot down the missile if it crosses over Japanese territory, a move which Pyongyang has already said it would consider an "act of war".
Hillary Clinton, the US Secretary of State, has warned any launch would threaten to end the six-party talks over Pyongyang's nuclear weapons programme. The talks have been stalled since December in a dispute over how to verify its disarmament.
"This provocative action, in violation of the United Nations mandate, will not go unnoticed and there will be consequences," she said while on a visit to Mexico, warning that the US would put the issue before the UN Security Council for additional sanctions.
It is unclear if China, Pyongyang's only major ally which has held talks with senior figures from both North and South Korea in the last week, would support a US move to deepen sanctions.