China is deploying a large number of naval and coast guard vessels across East Asian waters, at one point more than 100, in the largest maritime show of force to date, according to four sources and intelligence reports.

China is in the middle of what is traditionally a busy season for military exercises, though the People’s Liberation Army has not made any announcements of large-scale officially named drills.

Still, the rise in activity is happening as China and Japan are in a diplomatic crisis after Japanese Prime Minister Sanae Takaichi said last month that a hypothetical Chinese attack on democratically ruled Taiwan could trigger a military response from Tokyo.