During their impromptu summit at the inter-Korean border on June 30, U.S. President Donald Trump and North Korean leader Kim Jong-un agreed to relaunch working-level talks that have been stalled since their no-deal summit in Hanoi in February.

   Washington has repeatedly called for the talks to be kickstarted. But Pyongyang has yet to accede to those calls and has criticized both Seoul's plan to stage a combined military exercise with the U.S. and its purchase of advanced weapons systems from Washington.

   The ASEAN meetings here this week were expected to set the stage for talks between U.S. Secretary of State Mike Pompeo and North Korean Foreign Minister Ri Yong-ho. But Ri abruptly canceled his trip to Bangkok for unspecified reasons.

   Commenting on the intentions behind the North's projectile launches, the official raised the possibility that they could be aimed at enhancing its missile technology before the start negotiations, which would make it difficult to conduct such tests.

   "As the leaders (of the U.S. and the North) agreed to resume the working-level talks, I think (the North Koreans) will come out sooner or later," the official said.

   Touching on Washington's intermediary role between its two Asian allies, Seoul and Tokyo, the official said that the U.S. had made last-minute diplomatic efforts on Thursday night, the eve of Japan's removal of South Korea from its list of trusted trade partners.

   "I can say that (the U.S. side) was busy making moves (to help ease the dispute) until last night," the official said.

   The decision to drop Seoul from the whitelist came after Japan imposed tighter controls last month on exports to Korea of three key high-tech materials. Seoul has cast the moves as a political retaliation for last year's Supreme Court rulings against Japanese firms over wartime forced labor.

   The U.S. has proposed a "standstill agreement" to allow time to work out a negotiated solution between its allies, but Tokyo rejected the proposal, Kim Hyun-chong, Seoul's deputy national security advisor, has said.

   On the rejection of the proposal, Japanese Foreign Minister Taro Kono has claimed that it was a matter that Japan's Ministry of Economy, Trade and Industry is in charge of, the official at Seoul's foreign ministry said.

   During her trilateral talks with Pompeo and Kono in Bangkok on Friday, Kang was said to have mentioned the issue of South Korea's bilateral military intelligence-sharing deal with Japan, named the General Security of Military Information Agreement (GSOMIA).

   Seoul has hinted that it could review whether to renew the GSOMIA, seen as a rare symbol of security cooperation with Tokyo.

The deal is to be renewed annually unless either side opposes its continuation.

   "Our side has clearly said that we cannot help but put everything on the table and take it into consideration," the official said. The U.S. side did not make any direct comment on the GSOMIA issue, the official added.

   The official said there may need to be some "cooling-off"

period between Seoul and Tokyo in the wake of Japan's latest export restriction.