Geopolitical stresses in the Indo-Pacific are increasing and intensifying. These stresses derive from China’s more assertive regional behaviour; growing alignments between China and Russia on the one hand and Russia and North Korea on the other; and most recently from the apparent recalibration of United States foreign policy under the second Trump administration. They have magnified Japan’s significance as a strategic actor both in the Indo-Pacific and beyond. As such, it is of global importance whether Japan can meet the grand-strategic goals that it established in its 2022 National Security Strategy, National Defense Strategy and Defense Buildup Program. This Adelphi book evaluates Japan’s new grand strategy, considering whether it and associated reforms are sufficiently robust to fulfil Japan’s goal of ensuring its security even in the scenario of a Chinese attack on Taiwan.