A U.S. State Department report said that North Korea may have clandestine nuclear facilities in addition to the main Yongbyon nuclear complex, raising the specter of nuclear weapons proliferation in the communist state.

The 2015 Report on Adherence to and Compliance with Arms Control, Nonproliferation and Disarmament Agreements and Commitments also suggested that Pyongyang may have no intention to comply with its denuclearization commitments.

Pyongyang imploded the cooling tower at the Yongbyeon facility in June 2008 with much fanfare, inviting the international media to cover the event. However, Pyongyang conducted two nuclear tests after that event: It conducted its second nuclear test in 2009 after informing the International Atomic Energy Agency that it would resume its nuclear weapons program and quit the six-party talks; it conducted the third nuclear test in 2013 in violation of U.N. sanctions.

It has been suspected for some time that North Korea may be operating other nuclear facilities at different sites around the country, including additional uranium enrichment sites which cannot be easily detected. However, this time a U.S. State Department report has raised the possibility, saying “The U.S. believes there is a clear likelihood of additional unidentified nuclear facilities” in North Korea.

The U.S. State Department report also said that Pyongyang restarted the 5-megawatt reactor in 2013 and is constructing a light water reactor that could be used to justify having uranium enrichment technology that could then be used to produce fissile materials for nuclear weapons.

The report said that North Korea’s statements and activities did not signal any intention or commitment to denuclearization despite the continued demand by the U.S. to resume the stalled six-party talks, and called attention to the fact that the North Korean nuclear activities of the past year are in violation of the U.N. Security Council resolution.

With the Obama administration in its final stretch, it remains to be seen what kind of progress will be made in the effort to achieve the nuclear disarmament of North Korea. Obama has accomplished the normalization of ties with Cuba and is close to an Iranian nuclear deal. If he can resolve the North Korea nuclear issue, it will be a triple crown for the U.S. president.

The Obama administration appears at the moment to be focused on checking China’s rising power, preferring to exercise “strategic patience” with North Korea. While this might take away from attention on North Korea, Obama could also exert greater pressure on China to elicit more cooperation from North Korea on the denuclearization effort. China should do more to force Pyongyang back to the negotiating table.