North Korea has notified Japan of plans to launch a satellite by June 4, Japanese media reported Monday citing the coast guard, after Seoul said Pyongyang was preparing to put another military spy satellite into orbit.

The Japanese Coast Guard said the eight-day launch window began at midnight Sunday into Monday, with North Korea’s notice designating three maritime danger zones near the Korean peninsula and the Philippines island of Luzon where the satellite-carrying rocket’s debris might fall, according to the Kyodo news agency.

Officials from the United States, Japan and South Korea agreed in a phone call to urge Kim Jong Un’s regime to suspend the plan, as any launch using ballistic missile technology would violate UN resolutions, Kyodo reported.

Nuclear-armed North Korea launched its first reconnaissance satellite last November in a move that drew international condemnation, with the United States calling it a “brazen violation” of UN sanctions.

Experts say that spy satellites could improve Pyongyang’s intelligence-gathering capabilities, particularly over fierce rival South Korea, and provide crucial data in any military conflict.

Seoul said on Friday that South Korean and US intelligence authorities were “closely monitoring and tracking” presumed preparations for the launch of another military reconnaissance satellite.

The suspected preparations were detected in North Korea’s Tongchang-ri county, Seoul said, which is home to the isolated country’s Sohae Satellite Launching Ground. It was also where the North staged three satellite launches last year, with only the final one being successful.

Seoul has said the North received technical help from Russia for that satellite launch, in return for sending Moscow weapons for use in the war in Ukraine.

The warning from the North comes as Seoul, Beijing and Tokyo’s top leaders are due to meet in South Korea on Monday for their first summit in nearly five years, though differing political stances mean North Korea is not expected to be on the table.