INCHEON -- A senior US diplomat on Sunday called North Korea's recent announcement that it would stop nuclear and missile tests a "very positive" step and emphasized the need for close coordination with US allies in the run-up to the historic summits planned with the reclusive state.

Susan Thornton, acting US assistant secretary of state for East Asian and Pacific Affairs, made the remarks upon arriving at Incheon International Airport, west of Seoul.

"I think that is very positive. Of course we are going to be doing a lot of close coordination with the ROK, allies and partners this week. Maybe I will have more to say after the meetings this week. Very happy to be here," she said. ROK refers to South Korea's official name, the Republic of Korea.

"They said they are going to stop tests. ... They had said that previously. So it's a good sign that they are saying it again," she added.

Asked whether the steps announced by the North could be seen as part of the so-called "concrete action" the US has asked for to confirm its seriousness about denuclearization, she said, "We'll see."

During her three-day trip, she is to meet Seoul officials, including Foreign Minister Kang Kyung-wha and top nuclear envoy Lee Do-hoon.

Her visit here comes a day after North Korea announced its decision to stop nuclear and intercontinental ballistic missile tests and shut down its nuclear test site located in the north of the country.

South and North Korea are set to hold a summit on Friday, which will likely be followed by separate talks between the leaders of the US and the North either in May or early June. The denuclearization of the North is expected to top the agendas of both talks.(Yonhap)