CNN says U.S. intelligence authorities have detected signs that suggest North Korea has restarted its main nuclear facility at Yongbyon.

CNN issued the report Thursday as it quoted several U.S. intelligence officials.

The report says movements suggesting the North has restarted its main reactor have been spotted in the last few days, which, according to the officials, may signal that the North has begun nuclear reprocessing.

Officials from the U.S. State Department didn’t elaborate on the reprocessing discussion. Department spokesman Ian Kelly said Wednesday that although he will not comment on any intelligence matters, a restart of the reactor by the North would clearly be seen as a provocative act.

Meanwhile, a number of U.S. media outlets say that no irregular moves by the North’s military have been detected.