Ruth Kuang-chuang who is a senior official with the U.S. Department of State, is quoted as saying the U.S. intends to maintain a dialogue with North Korea, but he did not elaborate. His remarks were made as he was returning from an official visit in Urumqi, China’s capital.

“There are still many areas in which the US is concerned. These include potential further North Korean nuclear and missile tests that could lead to further proliferation of weapons of mass destruction, and the North Korean government’s ongoing harassment and mistreatment of foreign nationals.”

The New York Times reported that North Korea could be about to carry out another nuclear weapon test after the U.S and South Korea concluded there was “sufficient evidence” that Pyongyang has developed a rocket that can be fired to Mount Mantap in Mount Paektu, a peak 20,000 feet high, but also for another new long range missile in the next five years.

The North Korean Central News Agency said there were also plans to launch a missile in the near future containing an “improved” hydrogen bomb, along with a payload similar to the B2-B, a nuclear-capable missile first tested in 1988.

The Associated Press reported late Thursday that the two North Korean agents arrested in Beijing — in one of their last stops in the country after the arrests in Beijing of two other defectors from its security staff — are both agents for the North’s General Bureau of Investigation, not foreign intelligence agents.

One of them was identified as Kim Jong-chol, the older of the two as Kim was 30 when he first joined North Korea in 1978. He was an adviser to the first leader of a new generation of young elites who came to power in the mid 1990s and have become notorious as the North’s secret agents. The other was Kim Chol, who was a “former student of South Korean intelligence” as a teenager.

North Korean officials previously linked to the agency have claimed that they were working for the U.S. and South Korea to identify “targets of opportunity” and that they would bring back information useful in developing nuclear and missile systems.

The arrests drew swift denials from both North Korea’s ambassador to China, Kim In Ryong, and China’s foreign ministry spokesman Hong Lei.

“The accusations are absolutely baseless. They have absolutely no basis,” Hong wrote on his Twitter account.