WASHINGTON (Yonhap) ― The United States hopes that South Korea and Japan will make a concerted effort to promote the “healing” of the legacy from their shared history, especially in the 20th century, a key U.S. government official on Asia said Tuesday.

“They are both dealing with the legacy of very, very sensitive and very difficult issues, historical issues from the 20th century.

These legacy issues can’t be solved by any one party alone,” Daniel Russel, the assistant secretary of state for East Asian and Pacific affairs, said at a Senate hearing.

His remarks suggest that the Obama administration is not supporting Seoul’s view that Japan’s conservative Shinzo Abe administration is fully responsible for the drawn-out standoff between the neighboring countries.

Russell stressed the urgency of the two sides showing “prudence and restraint” in dealing with historical issues.

“It is important to handle them in a way that promotes healing,” he said.

The veteran diplomat said strategic cooperation among the U.S., South Korea and Japan is crucial in regional security, especially given North Korea’s threats and other regional uncertainties.

“No one can afford to allow the burdens of history to prevent us from building a secure future,” he said.

Also joining the hearing on Northeast Asia, David Helvey, a ranking Pentagon official, noted the importance of trilateral security cooperation.

“The Department of Defense encourages a healthy and open U.S., Republic of Korea and Japan relationship,” said Helvey, the deputy assistant secretary of defense for East Asia.

To that end, he added, the U.S. will continue to look for opportunities for the three countries to exercise together and to use the defense trilateral talks to promote cooperation, dialogue and transparency between Tokyo and Seoul.

On the issue of the wartime operational control (OPCON) transfer, he said the allies are reviewing whether the agreed-upon timing, December 2015, is appropriate “in the context of the changing security environment, particularly in North Korea.”

“The OPCON transition has always been conditions-based,” he added. “And we continue to assess and review the security situation on the Korean Peninsula in the context of the implementation of the strategic alliance 2015 plan.”

South Korea earlier agreed to take over its wartime OPCON from the U.S. as of December 2015, but it has requested a delay in the transfer, citing North Korea’s growing military threats.

Meanwhile, Russel, the State Department official, said there is no “credible indications” that North Korea is prepared to come into compliance with international obligations despite its recent peace overtures.

He said North Korea has shown a pattern of provocations followed by charm offensives aimed at eliciting concessions and rewards from the U.S., South Korea and the international community.

“We will not accept North Korea as a nuclear-armed state,” he added. “We will not reward the DPRK (North Korea) merely for returning to dialogue.”