Correction: An earlier version of this article incorrectly stated a missile had been placed on a long-range missile launch pad in North Korea, when reports actually indicated construction of a long-range rocket had been observed near Pyongyang and that upgrades to the Tonghang-ni launch pad had been upgraded.

Satellite imagery revealed modifications to a long-range launch pad in North Korea have been completed and that construction of a long-range rocket had been observed at a weapons factory near Pyongyang, South Korean intelligence sources told Yonhap News Agency on Wednesday.

The completion of an upgrade, an anonymous government source said, had been observed on the primary rocket launch pad at