The South Korean government said Friday it is closely communicating with Japan and the US over North Korea extending an invitation to Japanese Prime Minister Fumio Kishida a day earlier.

An official in Seoul said that any exchanges between Tokyo and Pyongyang “must unfold in a way that aids efforts for denuclearizing North Korea.”

North Korean leader Kim Jong-un’s sister Yo-jong said late Thursday that North Korea is open to “a new future” with Japan, if Kishida is “willing to make the necessary political decisions.”

“If Japan can leave behind its bad habits of unjustly interfering with our rights to self-defense ... there is no reason why the two countries cannot get closer, and the day may come when the Japanese prime minister visits Pyongyang,” she said in a statement carried by the North Korean official Korean Central News Agency.

The statement came in response to the Japanese prime minister telling his parliament last week that he would hold talks with Kim.

The US envoy on North Korean human rights, Julie Turner, said that Washington supports its allies engaging in dialogues with North Korea, speaking to the media about Kishida considering a summit with Kim.

In Seoul, top security officials have been closely watching North Korea as it tries to develop ties with Japan, noting that the aim of North Korea is to weaken South Korea’s cooperation with Japan and the US.

Earlier this year, Kim sent Kishida a letter offering condolences over the deadly earthquake that hit central Japan on New Year’s Day in a rare move apparently intended to boost relations.

Such unusual gestures from North Korea are an “attempt to undermine the security cooperation between South Korea and Japan,” the Minister of National Defense in Seoul Shin Won-sik said in an interview with The Korea Herald last month.

“While it is difficult to comment on the specifics of the possible diplomatic relations between Japan and North Korea, our military will continue the three-way security cooperation with the US and Japan to deter and counter North Korea’s escalating nuclear and missile threats,” the defense chief said.

The director of the National Intelligence Service Cho Tae-yong said during a confirmation hearing in January that he sees it as unlikely Japan will answer North Korea’s calls for talks. He was responding to questions from National Assembly members.

“Japan and North Korea have been unable to narrow their differences over the North’s abduction of Japanese citizens, which is one of the major stumbling blocks in the bilateral relations. It seems unlikely that diplomatic talks will happen without some concessions from either side,” he said, then as a nominee.

“But if North Korea is determined to create some gaps in the trilateral coordination among South Korea, Japan and the US, it would do whatever possible to push for talks with Japan,” he said.

Cho, who was the national security advisor before he assumed office as the spy chief in January, noted that Kishida has said he was willing to hold a summit with the North Korean leader.