Choosing his words carefully, Chief Cabinet Secretary Hiroyuki Hosoda voiced regret Friday over clandestine uranium enrichment experiments conducted in South Korea in 2000.
Seoul is a key ally of Tokyo in ongoing negotiations over North Korea’s nuclear ambitions.
Responding to questions about secret experiments involving South Korean scientists that produced weapons-grade uranium, Hosoda told a morning news conference that “it would be regrettable if true.”
On Thursday, South Korea admitted that researchers had conducted such experiments — in which a total of 0.2 gram of uranium was enriched in January and February 2000 — without the knowledge of the government.
The tests were soon halted and the uranium was destroyed, it said.
Hosoda refrained from directly criticizing the South Korean government.
“We don’t know details, but it is true that something that should have been managed by the International Atomic Energy Agency had not been reported to it,” he said.
“Of course, the sole purpose of the enrichment (experiment) appears to have been academic research.”
By playing down the matter, Tokyo was apparently trying to avoid complicating ongoing diplomatic maneuvers aimed at getting Pyongyang to abandon its nuclear program.
The six-party diplomatic process involves Japan, the United States, China, Russia and the two Koreas.
But some observers believe South Korea’s tests could affect efforts to stymie North Korea’s nuclear ambitions.
Foreign Minister Yoriko Kawaguchi told a separate news conference that she views the enrichment tests as “a separate issue” from the six-party talks.
She said it is a matter to be settled between South Korea and the IAEA.
“The South Korean government and the IAEA have started talks on this problem, and we think it is now being properly handled,” Kawaguchi said.
Hosoda said it would be impossible for a state-linked institute in Japan to enrich uranium using similar technologies without the government knowing, given the strict budget-screening process.
Talks on North’s nukes
Japan, South Korea and the U.S. will hold informal senior working-level talks on North Korea’s nuclear ambitions next week in Tokyo, Foreign Ministry sources said Friday.