Citing defense officials who asked not to be identified, the newspaper said the planning included programs for striking a plutonium-reprocessing facility at Yongbyon with commando raids or precision-guided missiles.
The planning, which has been under way several months, means only that US military forces would be ready if President George W. Bush were to order attacks, the newspaper said.
Defense officials said China's condemnation of North Korea's nuclear test and Beijing's support for United Nations sanctions were a key factor in the Bush administration's decision to speed up its planning, The Washington Times reported.
The administration regards the new level of Chinese support as a "green light" for more aggressive military planning, the report said.
A Pentagon official was quoted as saying that the Defense Department was considering "various military options" for removing North Korea's nuclear program.
The Bush administration recently affirmed its commitment to both South Korea and Japan that it would use nuclear weapons to deter North Korea, another senior defense official told the newspaper.
"We will resort to whatever force levels we need to have to defend the Republic of Korea. The nuclear deterrence is in place," the official said.

Copyright Reuters, 2006