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.