Vice President William Lai became Taiwan’s most senior official to visit Japan in five decades on Monday, when he paid his condolences to former Prime Minister Shinzo Abe, who was assassinated by a gunman.

According to a Japanese Foreign Ministry official, Lai was in Japan on a private visit to pay his condolences following Abe’s death on Friday.

The official refused to provide any other information, including how long Lai would stay in Japan.

“We believe this guy is still in Japan, but on a private visit to offer his respects as Abe’s buddy.”

Taiwan’s Presidential Office declined to comment, but noted that Lai had been “a close friend of Abe and his family for many years.”

The Foreign Ministry of Taiwan stated it would not comment on Lai’s “personal schedule.” It didn’t go into detail.

According to Taiwan’s official Central News Agency, Lai is the most senior official to visit Japan since Tokyo severed diplomatic ties with Taipei in 1972 and established relations with Beijing.

According to a senior member from the ruling Democratic Progressive Party, Lai paid a visit to Abe’s Tokyo house to offer condolences and will attend his burial on Tuesday.

Japan, like other nations, has no formal diplomatic connections with the Chinese-claimed island, but some prominent Japanese officials have grown increasingly vocal in recent years about their support for Taiwan.