Just minutes after U.S. House Speaker Nancy Pelosi became the highest-ranking American official to set foot in Taiwan in 25 years, a furious China announced a spate of military exercises that would effectively encircle the democratic island.

But the drills, which China characterized as a “series of targeted military actions” in response to Pelosi’s visit, aren’t just intended to keep Taiwan and the United States in check. They’re also a clear warning to Japan, experts say, with some of its far-flung southwestern islands sandwiched between planned exercise zones, according to coordinates released by the Chinese military.

“Those plans show that the Sakishima Islands, including Yonaguni, Ishigaki, and Miyako, could be affected by People’s Liberation Army operations as they assume the PLA is operating to the east of Taiwan,” said Tetsuo Kotani, a professor of global studies at Meikai University.