A USA defense official downplayed the importance of Sohai and said the site was not a priority in terms of monitoring the North's denuclearisation efforts.
Their last phone conversation came soon after the US-North Korea summit in June.
Previously, Reuters said that a report by independent experts monitoring the implementation of United Nations sanctions had been submitted to the Security Council North Korea sanctions committee, saying that Pyongyang has not stopped its nuclear and missile programs.
In an article titled, "There is no reason to ignore the declaration of the end of war", North Korean outlet Uriminzokkiri stated, "If with an end-of-war declaration the military confrontation between North Korea and the United States ends and an atmosphere advantageous to the development of trust will be created, it would build anticipation for new progress on North Korea-U.S. relations". The two were engaged in a devastating 1950s conflict that ended in an armistice but no official peace treaty, and they have been technically at war at ever since.
North Korea has insisted that any moves toward denuclearisation on its part must be on a step-by-step basis in return for concessions from the U.S. and its allies.
"I didn't know my father would cry this much", said Byung-oh's son. The joint statement released from the Trump-Kim summit spoke only in general terms of the need "to work toward complete denuclearisation of the Korean Peninsula"-a vague phrase that Washington and Pyongyang interpreted differently".
Analysts say a declaration to officially end the war would make it easier for Pyongyang to steer the discussions with Washington toward a peace treaty, diplomatic recognition, security assurance and economic benefits.
However, Pyongyang has given no indication it is willing to give up its nuclear weapons unilaterally as the Trump administration has demanded.
Ahead of a third planned summit next month, Moon has promised major changes created to keep the peace process on track. "I stopped [North Korea's] nuclear testing".
Duyeon Kim, an adjunct senior fellow at the Center for a New American Security, said: "The Singapore summit wasn't a nuclear deal and there's no agreement between Washington and Pyongyang that would encourage North Korea to act any differently".
Millions of people were swept apart by the 1950-53 Korean War, which left the peninsula split by the impenetrable Demilitarised Zone (DMZ) and separated brothers and sisters, parents and children and husbands and wives.
Other companies, on the other hand, said today that restrictions on Chinese tour groups announced earlier this month are still in place, though dates vary as to when they will be allowed to resume tours to the DPRK.
North Korea's media also urged USA to lift the sanctions on Pyongyang, adding that improvement of ties and sanctions can't go together.
Japanese Prime Minister Shinzo Abe has discussed North Korea-related issues with US President Donald Trump. He noted that he asked Trump for his country's cooperation.
One of the Russian tankers, the Patriot, violated sanctions by loading fuel on two North Korea ships early this year which are on the US sanctions list.