The United States is making denuclearization the top priority on its North Korea policy, a ranking U.S. diplomat said Thursday, amid the long-stalled six-party talks on ending the communist country's nuclear program.

Wendy Sherman, U.S. undersecretary of state for political affairs, also said that there is "no daylight" between Seoul and Washington in dealing with North Korea, stressing that Washington supports Seoul's bid for inter-Korean dialogue.

"We have the same policy as the Republic of Korea does and that is to ultimately have a denuclearized peninsula. Denuclearization is the first priority where North Korea is concerned," Sherman told a group of reporters in Seoul after meeting with her South Korean counterpart, Cho Tae-yong.

Sherman arrived in Seoul on Wednesday for a two-day visit to discuss North Korea's nuclear program and other bilateral issues.

The Seoul visit was the second leg of her three-nation tour that includes China and Japan. She will leave for Tokyo later in the day.

"There is no daylight between us ... between our two countries about North Korea's policies," Sherman said at the start of the meeting. "We're both committed to denuclearization and unification under a democratic process here on the peninsula."

The visit came amid growing concerns here that Washington's tougher pressure on North Korea may conflict with Seoul's efforts to improve inter-Korean relations.

Washington imposed fresh sanctions on Pyongyang early this month for its alleged hacking of Sony Pictures over a comedy film revolving around a plot to kill its leader Kim Jong-un.

While Washington has taken a tougher stance on the North, South Korea is awaiting a response from North Korea for its proposal to have high-level talks.

U.S. President Barack Obama recently said he believes North Korea is bound to collapse, sparking a flurry of speculation that Washington's policy toward North Korea is to heap pressure on Pyongyang, not to pursue engagement.

In a meeting with reporters in Tokyo on Wednesday, Hwang Joon-kook, Seoul's top nuke envoy, dismissed the view that Seoul and Washington are not on the same page.

He said it is a misunderstanding to believe that Washington has shut its doors for dialogue with the North.

Sherman's visit to Seoul came amid the long-stalled six-party talks aimed at ending North Korea's nuclear weapons program.

The six-party talks on North Korea's nuclear programs -- involving the two Koreas, the U.S., China, Japan and Russia -- have been dormant since late 2008, when Pyongyang walked away from the bargaining table.

Seoul and Washington have insisted that the North should first show its sincere commitment toward denuclearization before the six-party talks can be resumed, while North Korea has demanded they be restarted unconditionally.

Sherman declined to comment on what would be the minimum preconditions for the resumption of the denuclearization talks, only saying that the North should show its sincerity toward denuclearization in a "concrete" manner.

"North Korea needs to show concretely that it's taking steps towards denuclearization. There are many ways to do so," she said.

The North offered on Jan. 10 to temporarily halt nuclear tests if the U.S. suspends its annual military exercises with South Korea this year, a proposal flatly rejected by Seoul and Washington.

Sherman became the U.S. undersecretary of state for political affairs in September 2011. She served as the U.S. State Department's special coordinator for North Korea policy from 1997 to 2001. (Yonhap)