Washington ? North Korea has reactivated a nuclear reactor, U.S. officials said Wednesday, in what could be a first step toward production of additional nuclear weapons.

U.S. intelligence officials said a telltale plume was spotted at the reactor shortly after Secretary of State Colin Powell said Pyongyang had made “a wise choice if it’s a conscious choice” not to restart the reactor.

Powell was airborne over the Pacific at the time, heading home Tuesday after a visit to South Korea.

North Korea currently has the ability to produce five or six plutonium bombs from 8,000 spent fuel rods in a matter of a few months.

The reactivation, disclosed by two officials familiar with the North’s military activities, could enable the North Koreans to build additional weapons in about a year. The Bush administration believes that North Korea now has one or two nuclear weapons.

South Korean Prime Minister Goh Kun said he could not confirm the report. “One of the top priorities of the new government is to try to end the nuclear issue peacefully, in close cooperation with the United States,” he said.

The disclosure of the new activity came a day after the installation of South Korea’s new president, Roh Moo-hyun. Goh took office today.

Powell attended Roh’s inauguration and announced afterward that the United States was donating 40,000 metric tons of food to North Korea, with an additional 60,000 metric tons later in the year.

The administration has consistently said that food assistance for North Korea would not be affected by political considerations. Powell blamed continued hunger in North Korea on Pyongyang’s guns-over-butter policies.