South Korea said on Friday that North Korea was making genuine plans to test fire a missile, but warned Pyongyang that its actions were a miscalculation and would not change US policy.
Preparations for the launch of a Taepodong-2 with a range of up to 6,700 kms have been underway for several weeks at Musudanri on the remote northeast coast of North Korea.
US reports have said a launch was imminent.
Unification Minister Lee Jong-Seok, the minister responsible for handling North Korean relations, said he believed North Korea had intended to launch a missile all along.
The minister said before parliament that he did not believe North Korea's preparations were a mere bluff.
"I think it has been moving for a real launch," he said.
Lee said North Korea hoped to influence US policy, but had miscalculated, as Washington would not bow to pressure from Pyongyang.
"The United States will not make a compromise even if North Korea fires a missile," he added.