The U.S. is urging North Korea to demonstrate to the U.S. and others that it is serious about following through with its denuclearization commitments.

State Department spokesman Philip Crowley made the remark in a Wednesday briefing.

However, Crowley did not confirm a report by Voice of America in which the broadcaster said that North Korea has completed a launch tower at its second missile launch facility.

On providing food aid to Pyongyang, he said Washington is closely watching the situation.